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But now —" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/alter-table-outage.yaml#steps[4]", "session": "B", "sql": "ALTER TABLE accounts ADD COLUMN note text", "fields": { "B": "ALTER TABLE accounts ADD COLUMN note text", "blocks": "p1", "tl": "ALTER TABLE … ADD COLUMN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "ALTER TABLE accounts ADD COLUMN note text" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/alter-table-outage.yaml#steps[5]", "session": null, "sql": null, "fields": { "note": "— every new query on the table queues behind the *waiting* ALTER. This is the outage." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"ALTER TABLE accounts ADD COLUMN note text\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "ALTER TABLE accounts ADD COLUMN note text" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/alter-table-outage.yaml#steps[6]", "session": "C", "sql": "SELECT balance FROM accounts WHERE id = 1", "fields": { "C": "SELECT balance FROM accounts WHERE id = 1", "blocks": "p2", "tl": "SELECT — just a read!" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"ALTER TABLE accounts ADD COLUMN note text\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "ALTER TABLE accounts ADD COLUMN note text" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT balance FROM accounts WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/alter-table-outage.yaml#steps[7]", "session": "M", "sql": "SELECT waiter.application_name AS waiter, blocker.application_name AS blocker\nFROM pg_stat_activity waiter\nJOIN pg_stat_activity blocker ON blocker.pid = ANY (pg_blocking_pids(waiter.pid))\nWHERE waiter.wait_event_type = 'Lock'\nORDER BY waiter.application_name, blocker.application_name\n", "fields": { "M": "SELECT waiter.application_name AS waiter, blocker.application_name AS blocker\nFROM pg_stat_activity waiter\nJOIN pg_stat_activity blocker ON blocker.pid = ANY (pg_blocking_pids(waiter.pid))\nWHERE waiter.wait_event_type = 'Lock'\nORDER BY waiter.application_name, blocker.application_name\n", "expect": [ { "waiter": "B", "blocker": "A" }, { "waiter": "C", "blocker": "B" } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"ALTER TABLE accounts ADD COLUMN note text\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT balance FROM accounts WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "ALTER TABLE accounts ADD COLUMN note text" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT balance FROM accounts WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/alter-table-outage.yaml#steps[8]", "session": null, "sql": null, "fields": { "note": "Only when A ends does the pile-up drain — migration first, then the reads." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"ALTER TABLE accounts ADD COLUMN note text\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT balance FROM accounts WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "ALTER TABLE accounts ADD COLUMN note text" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT balance FROM accounts WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/alter-table-outage.yaml#steps[9]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "tl": "COMMIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"ALTER TABLE accounts ADD COLUMN note text\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT balance FROM accounts WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "ALTER TABLE accounts ADD COLUMN note text" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT balance FROM accounts WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/alter-table-outage.yaml#steps[10]", "session": "B", "sql": "ALTER TABLE accounts ADD COLUMN note text", "fields": { "success": "p1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"ALTER TABLE accounts ADD COLUMN note text\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT balance FROM accounts WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT balance FROM accounts WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/alter-table-outage.yaml#steps[11]", "session": "C", "sql": "SELECT balance FROM accounts WHERE id = 1", "fields": { "success": "p2" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT balance FROM accounts WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] }, "current": { "sha256": "dceac638b22531fda2f2a4a231de64bbbb71fad2334df7231520d2039eb79650", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/alter-table-outage.yaml#steps[0]", "session": null, "sql": null, "fields": { "note": "A reads accounts inside an explicit transaction and retains its table lock." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/alter-table-outage.yaml#steps[1]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/alter-table-outage.yaml#steps[2]", "session": "A", "sql": "SELECT balance FROM accounts WHERE id = 1", "fields": { "A": "SELECT balance FROM accounts WHERE id = 1", "tl": "SELECT (a long-lived transaction)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/alter-table-outage.yaml#steps[3]", "session": null, "sql": null, "fields": { "note": "The migration needs ACCESS EXCLUSIVE, so it waits for A. Expected. But now —" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/alter-table-outage.yaml#steps[4]", "session": "B", "sql": "ALTER TABLE accounts ADD COLUMN note text", "fields": { "B": "ALTER TABLE accounts ADD COLUMN note text", "blocks": "p1", "tl": "ALTER TABLE … ADD COLUMN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "ALTER TABLE accounts ADD COLUMN note text" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/alter-table-outage.yaml#steps[5]", "session": null, "sql": null, "fields": { "note": "C's new SELECT now waits behind the queued ALTER request." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"ALTER TABLE accounts ADD COLUMN note text\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "ALTER TABLE accounts ADD COLUMN note text" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/alter-table-outage.yaml#steps[6]", "session": "C", "sql": "SELECT balance FROM accounts WHERE id = 1", "fields": { "C": "SELECT balance FROM accounts WHERE id = 1", "blocks": "p2", "tl": "SELECT — just a read!" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"ALTER TABLE accounts ADD COLUMN note text\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "ALTER TABLE accounts ADD COLUMN note text" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT balance FROM accounts WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/alter-table-outage.yaml#steps[7]", "session": "M", "sql": "SELECT waiter.application_name AS waiter, blocker.application_name AS blocker\nFROM pg_stat_activity waiter\nJOIN pg_stat_activity blocker ON blocker.pid = ANY (pg_blocking_pids(waiter.pid))\nWHERE waiter.wait_event_type = 'Lock'\nORDER BY waiter.application_name, blocker.application_name\n", "fields": { "M": "SELECT waiter.application_name AS waiter, blocker.application_name AS blocker\nFROM pg_stat_activity waiter\nJOIN pg_stat_activity blocker ON blocker.pid = ANY (pg_blocking_pids(waiter.pid))\nWHERE waiter.wait_event_type = 'Lock'\nORDER BY waiter.application_name, blocker.application_name\n", "expect": [ { "waiter": "B", "blocker": "A" }, { "waiter": "C", "blocker": "B" } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"ALTER TABLE accounts ADD COLUMN note text\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT balance FROM accounts WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "ALTER TABLE accounts ADD COLUMN note text" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT balance FROM accounts WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/alter-table-outage.yaml#steps[8]", "session": null, "sql": null, "fields": { "note": "A commits; B's standalone ALTER and C's read then complete." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"ALTER TABLE accounts ADD COLUMN note text\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT balance FROM accounts WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "ALTER TABLE accounts ADD COLUMN note text" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT balance FROM accounts WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/alter-table-outage.yaml#steps[9]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "tl": "COMMIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"ALTER TABLE accounts ADD COLUMN note text\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT balance FROM accounts WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "ALTER TABLE accounts ADD COLUMN note text" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT balance FROM accounts WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/alter-table-outage.yaml#steps[10]", "session": "B", "sql": "ALTER TABLE accounts ADD COLUMN note text", "fields": { "success": "p1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"ALTER TABLE accounts ADD COLUMN note text\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT balance FROM accounts WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT balance FROM accounts WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/alter-table-outage.yaml#steps[11]", "session": "C", "sql": "SELECT balance FROM accounts WHERE id = 1", "fields": { "success": "p2", "expect": [ { "balance": 100 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT balance FROM accounts WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] } }, "mirrors": [ { "scenario": "scenarios/postgres/03-locking/alter-table-outage.yaml", "transcript": "docs/postgres/03-locking/parts/alter-table-outage.md", "ledger": "docs/public/ledger.jsonl#scenario=postgres/03-locking/alter-table-outage.yaml", "llms": "docs/public/llms-full.txt#section=postgres/03-locking/alter-table-outage.yaml", "metadata": "lead included scenario claim supplies built description/TechArticle where configured" } ] }, { "id": "P14", "path": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml", "engine": "PostgreSQL", "observed_version": "18.6", "manual_version": "18", "evidence": { "scenarios": ["scenarios/postgres/03-locking/ddl-lock-timeout.yaml"], "official_manual_sections": [ "https://www.postgresql.org/docs/18/explicit-locking.html#LOCKING-TABLES", "https://www.postgresql.org/docs/18/sql-altertable.html", "https://www.postgresql.org/docs/18/runtime-config-client.html#GUC-LOCK-TIMEOUT", "https://www.postgresql.org/docs/18/sql-createindex.html#SQL-CREATEINDEX-CONCURRENTLY" ] }, "revisions": { "base": { "sha256": "55d751a32d3594319c0169c6184939abd71940481ee50fa39ffc1a5fafb74cf0", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[0]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[1]", "session": "A", "sql": "SELECT balance FROM accounts WHERE id = 1", "fields": { "A": "SELECT balance FROM accounts WHERE id = 1", "comment": "the same long transaction as before", "tl": "SELECT (long-lived txn) → holds ACCESS SHARE" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[2]", "session": null, "sql": null, "fields": { "note": "Same migration — but this time it gives up after 100ms instead of camping in the queue." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[3]", "session": "B", "sql": "SET lock_timeout = '100ms'", "fields": { "B": "SET lock_timeout = '100ms'" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[4]", "session": "B", "sql": "ALTER TABLE accounts ADD COLUMN note text", "fields": { "B.fails": "ALTER TABLE accounts ADD COLUMN note text", "error": "55P03", "tl": "ALTER TABLE … → gives up after 100ms" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[5]", "session": null, "sql": null, "fields": { "note": "No waiting ALTER in the queue means no outage: C's read is instant." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[6]", "session": "C", "sql": "SELECT balance FROM accounts WHERE id = 1", "fields": { "C": "SELECT balance FROM accounts WHERE id = 1", "expect": [ { "balance": 100 } ], "tl": "SELECT → instant, nothing queued behind the ALTER" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[7]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "tl": "COMMIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[8]", "session": null, "sql": null, "fields": { "note": "Retry the migration when it can actually get the lock — now it sails through." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[9]", "session": "B", "sql": "ALTER TABLE accounts ADD COLUMN note text", "fields": { "B": "ALTER TABLE accounts ADD COLUMN note text", "tl": "ALTER TABLE … (retry sails through)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] }, "current": { "sha256": "ec82d448b8084a17f51b836f60a70b02a9bfc99838b94747aca72b8030c1e9cc", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[0]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[1]", "session": "A", "sql": "SELECT balance FROM accounts WHERE id = 1", "fields": { "A": "SELECT balance FROM accounts WHERE id = 1", "comment": "the same long transaction as before", "tl": "SELECT (long-lived txn) → holds ACCESS SHARE" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[2]", "session": null, "sql": null, "fields": { "note": "Same migration — but this time it gives up after 100ms instead of camping in the queue." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[3]", "session": "B", "sql": "SET lock_timeout = '100ms'", "fields": { "B": "SET lock_timeout = '100ms'" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[4]", "session": "B", "sql": "ALTER TABLE accounts ADD COLUMN note text", "fields": { "B.fails": "ALTER TABLE accounts ADD COLUMN note text", "error": "55P03", "tl": "ALTER TABLE … → gives up after 100ms" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[5]", "session": null, "sql": null, "fields": { "note": "After B's timeout removes its request, C's read returns 100. No read during B's wait is tested." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[6]", "session": "C", "sql": "SELECT balance FROM accounts WHERE id = 1", "fields": { "C": "SELECT balance FROM accounts WHERE id = 1", "expect": [ { "balance": 100 } ], "tl": "SELECT after ALTER timeout → 100" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[7]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "tl": "COMMIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[8]", "session": null, "sql": null, "fields": { "note": "Retry the migration when it can actually get the lock — now it sails through." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[9]", "session": "B", "sql": "ALTER TABLE accounts ADD COLUMN note text", "fields": { "B": "ALTER TABLE accounts ADD COLUMN note text", "tl": "ALTER TABLE … (retry completes)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml#steps[10]", "session": "C", "sql": "SELECT column_name FROM information_schema.columns WHERE table_schema = 'public' AND table_name = 'accounts' AND column_name = 'note'", "fields": { "C": "SELECT column_name FROM information_schema.columns WHERE table_schema = 'public' AND table_name = 'accounts' AND column_name = 'note'", "expect": [ { "column_name": "note" } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] } }, "mirrors": [ { "scenario": "scenarios/postgres/03-locking/ddl-lock-timeout.yaml", "transcript": "docs/postgres/03-locking/parts/ddl-lock-timeout.md", "ledger": "docs/public/ledger.jsonl#scenario=postgres/03-locking/ddl-lock-timeout.yaml", "llms": "docs/public/llms-full.txt#section=postgres/03-locking/ddl-lock-timeout.yaml", "metadata": "lead included scenario claim supplies built description/TechArticle where configured" } ] }, { "id": "P15", "path": "scenarios/postgres/03-locking/deadlock-avoidance.yaml", "engine": "PostgreSQL", "observed_version": "18.6", "manual_version": "18", "evidence": { "scenarios": ["scenarios/postgres/03-locking/deadlock-avoidance.yaml"], "official_manual_sections": [ "https://www.postgresql.org/docs/18/explicit-locking.html#LOCKING-DEADLOCKS", "https://www.postgresql.org/docs/18/runtime-config-locks.html#GUC-DEADLOCK-TIMEOUT" ] }, "revisions": { "base": { "sha256": "191db2e320d5873f3c0807b1c58ce91a5283b6dfe0e5485119f87936a3a0066d", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[0]", "session": null, "sql": null, "fields": { "note": "Both transfers grab *all* their row locks up front, ordered by id." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[1]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[2]", "session": "A", "sql": "SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE", "fields": { "A": "SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE", "tl": "SELECT id IN (1,2) … FOR UPDATE → locks both, in id order" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[3]", "session": "B", "sql": "BEGIN", "fields": { "B": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[4]", "session": "B", "sql": "SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE", "fields": { "B": "SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE", "blocks": "p1", "tl": "SELECT id IN (1,2) … FOR UPDATE" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[5]", "session": null, "sql": null, "fields": { "note": "No cycle is possible: B parks at the first row and holds nothing A needs." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[6]", "session": "A", "sql": "UPDATE accounts SET balance = balance - 10 WHERE id = 1", "fields": { "A": "UPDATE accounts SET balance = balance - 10 WHERE id = 1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[7]", "session": "A", "sql": "UPDATE accounts SET balance = balance + 10 WHERE id = 2", "fields": { "A": "UPDATE accounts SET balance = balance + 10 WHERE id = 2" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[8]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "tl": "COMMIT → releases both" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[9]", "session": "B", "sql": "SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE", "fields": { "success": "p1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[10]", "session": "B", "sql": "UPDATE accounts SET balance = balance - 25 WHERE id = 2", "fields": { "B": "UPDATE accounts SET balance = balance - 25 WHERE id = 2" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[11]", "session": "B", "sql": "UPDATE accounts SET balance = balance + 25 WHERE id = 1", "fields": { "B": "UPDATE accounts SET balance = balance + 25 WHERE id = 1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[12]", "session": "B", "sql": "COMMIT", "fields": { "B": "COMMIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[13]", "session": "A", "sql": "SELECT owner, balance FROM accounts ORDER BY id", "fields": { "A": "SELECT owner, balance FROM accounts ORDER BY id", "expect": [ { "owner": "alice", "balance": 115 }, { "owner": "bob", "balance": 85 } ], "comment": "both transfers landed — same workload, zero deadlocks" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] }, "current": { "sha256": "a8ebbc981323e8cd67500dc74a2631db831b4c96e7d33a7eb93a5f19f43b414e", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[0]", "session": null, "sql": null, "fields": { "note": "Both transfers grab *all* their row locks up front, ordered by id." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[1]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[2]", "session": "A", "sql": "SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE", "fields": { "A": "SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE", "tl": "SELECT id IN (1,2) … FOR UPDATE → locks both, in id order" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[3]", "session": "B", "sql": "BEGIN", "fields": { "B": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[4]", "session": "B", "sql": "SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE", "fields": { "B": "SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE", "blocks": "p1", "tl": "SELECT id IN (1,2) … FOR UPDATE" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[5]", "session": null, "sql": null, "fields": { "note": "No cycle is possible: B parks at the first row and holds nothing A needs." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[6]", "session": "A", "sql": "UPDATE accounts SET balance = balance - 10 WHERE id = 1", "fields": { "A": "UPDATE accounts SET balance = balance - 10 WHERE id = 1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[7]", "session": "A", "sql": "UPDATE accounts SET balance = balance + 10 WHERE id = 2", "fields": { "A": "UPDATE accounts SET balance = balance + 10 WHERE id = 2" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[8]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "tl": "COMMIT → releases both" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[9]", "session": "B", "sql": "SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE", "fields": { "success": "p1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT id FROM accounts WHERE id IN (1, 2) ORDER BY id FOR UPDATE\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[10]", "session": "B", "sql": "UPDATE accounts SET balance = balance - 25 WHERE id = 2", "fields": { "B": "UPDATE accounts SET balance = balance - 25 WHERE id = 2" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[11]", "session": "B", "sql": "UPDATE accounts SET balance = balance + 25 WHERE id = 1", "fields": { "B": "UPDATE accounts SET balance = balance + 25 WHERE id = 1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[12]", "session": "B", "sql": "COMMIT", "fields": { "B": "COMMIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock-avoidance.yaml#steps[13]", "session": "A", "sql": "SELECT owner, balance FROM accounts ORDER BY id", "fields": { "A": "SELECT owner, balance FROM accounts ORDER BY id", "expect": [ { "owner": "alice", "balance": 115 }, { "owner": "bob", "balance": 85 } ], "comment": "both transfers committed in this schedule" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] } }, "mirrors": [ { "scenario": "scenarios/postgres/03-locking/deadlock-avoidance.yaml", "transcript": "docs/postgres/03-locking/parts/deadlock-avoidance.md", "ledger": "docs/public/ledger.jsonl#scenario=postgres/03-locking/deadlock-avoidance.yaml", "llms": "docs/public/llms-full.txt#section=postgres/03-locking/deadlock-avoidance.yaml", "metadata": "lead included scenario claim supplies built description/TechArticle where configured" } ] }, { "id": "P16", "path": "scenarios/postgres/03-locking/deadlock.yaml", "engine": "PostgreSQL", "observed_version": "18.6", "manual_version": "18", "evidence": { "scenarios": ["scenarios/postgres/03-locking/deadlock.yaml"], "official_manual_sections": [ "https://www.postgresql.org/docs/18/explicit-locking.html#LOCKING-DEADLOCKS", "https://www.postgresql.org/docs/18/runtime-config-locks.html#GUC-DEADLOCK-TIMEOUT" ] }, "revisions": { "base": { "sha256": "bd6dd9bd6c03fdd8fe13b7456964e356764d19c4f9f2e48471978af7efde46bb", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[0]", "session": "A", "sql": "SET deadlock_timeout = '10s'", "fields": { "A": "SET deadlock_timeout = '10s'", "comment": "In production the victim is effectively arbitrary — whichever waiter's deadlock_timeout (default 1s) fires first runs the check and aborts itself. We pin it here so the transcript is reproducible: B checks first." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[1]", "session": "B", "sql": "SET deadlock_timeout = '50ms'", "fields": { "B": "SET deadlock_timeout = '50ms'" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[2]", "session": null, "sql": null, "fields": { "note": "A transfers 10 from alice to bob; B transfers 25 from bob to alice." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[3]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[4]", "session": "A", "sql": "UPDATE accounts SET balance = balance - 10 WHERE id = 1", "fields": { "A": "UPDATE accounts SET balance = balance - 10 WHERE id = 1", "comment": "A locks alice", "tl": "locks alice (id=1)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[5]", "session": "B", "sql": "BEGIN", "fields": { "B": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[6]", "session": "B", "sql": "UPDATE accounts SET balance = balance - 25 WHERE id = 2", "fields": { "B": "UPDATE accounts SET balance = balance - 25 WHERE id = 2", "comment": "B locks bob", "tl": "locks bob (id=2)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[7]", "session": null, "sql": null, "fields": { "note": "A now needs bob's row (B has it) — it waits." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[8]", "session": "A", "sql": "UPDATE accounts SET balance = balance + 10 WHERE id = 2", "fields": { "A": "UPDATE accounts SET balance = balance + 10 WHERE id = 2", "blocks": "p1", "tl": "needs bob (id=2)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s", "pending": "UPDATE accounts SET balance = balance + 10 WHERE id = 2" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[9]", "session": null, "sql": null, "fields": { "note": "B now needs alice's row (A has it). A waits for B, B waits for A: a cycle." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\",\"pending\":\"UPDATE accounts SET balance = balance + 10 WHERE id = 2\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s", "pending": "UPDATE accounts SET balance = balance + 10 WHERE id = 2" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[10]", "session": "B", "sql": "UPDATE accounts SET balance = balance + 25 WHERE id = 1", "fields": { "B.fails": "UPDATE accounts SET balance = balance + 25 WHERE id = 1", "error": "40P01", "comment": "deadlock_detected — B is aborted…", "tl": "needs alice (id=1)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\",\"pending\":\"UPDATE accounts SET balance = balance + 10 WHERE id = 2\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s", "pending": "UPDATE accounts SET balance = balance + 10 WHERE id = 2" }, "B": { "phase": "explicit failed (database effects aborted; awaits transaction end)", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[11]", "session": null, "sql": null, "fields": { "note": "The victim's abort frees bob's row, so A's stuck UPDATE completes." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\",\"pending\":\"UPDATE accounts SET balance = balance + 10 WHERE id = 2\"}; B={\"phase\":\"explicit failed (database effects aborted; awaits transaction end)\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s", "pending": "UPDATE accounts SET balance = balance + 10 WHERE id = 2" }, "B": { "phase": "explicit failed (database effects aborted; awaits transaction end)", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[12]", "session": "A", "sql": "UPDATE accounts SET balance = balance + 10 WHERE id = 2", "fields": { "success": "p1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\",\"pending\":\"UPDATE accounts SET balance = balance + 10 WHERE id = 2\"}; B={\"phase\":\"explicit failed (database effects aborted; awaits transaction end)\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "explicit failed (database effects aborted; awaits transaction end)", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[13]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"explicit failed (database effects aborted; awaits transaction end)\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "explicit failed (database effects aborted; awaits transaction end)", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[14]", "session": "B", "sql": "ROLLBACK", "fields": { "B": "ROLLBACK" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"explicit failed (database effects aborted; awaits transaction end)\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[15]", "session": "A", "sql": "SELECT owner, balance FROM accounts ORDER BY id", "fields": { "A": "SELECT owner, balance FROM accounts ORDER BY id", "expect": [ { "owner": "alice", "balance": 90 }, { "owner": "bob", "balance": 110 } ], "comment": "A's transfer survived; B's evaporated — retry it" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } } ] }, "current": { "sha256": "715816bfadc774d3defc5ccf36bc870984bf3af9ecf768b0fe999bf7fabe3238", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[0]", "session": "A", "sql": "SET deadlock_timeout = '10s'", "fields": { "A": "SET deadlock_timeout = '10s'", "comment": "General victim choice must not be relied on. These unequal detection timeouts make B the observed victim in this controlled schedule; no universal minimum cycle duration is asserted." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[1]", "session": "B", "sql": "SET deadlock_timeout = '50ms'", "fields": { "B": "SET deadlock_timeout = '50ms'" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[2]", "session": null, "sql": null, "fields": { "note": "A transfers 10 from alice to bob; B transfers 25 from bob to alice." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[3]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[4]", "session": "A", "sql": "UPDATE accounts SET balance = balance - 10 WHERE id = 1", "fields": { "A": "UPDATE accounts SET balance = balance - 10 WHERE id = 1", "comment": "A locks alice", "tl": "locks alice (id=1)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[5]", "session": "B", "sql": "BEGIN", "fields": { "B": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[6]", "session": "B", "sql": "UPDATE accounts SET balance = balance - 25 WHERE id = 2", "fields": { "B": "UPDATE accounts SET balance = balance - 25 WHERE id = 2", "comment": "B locks bob", "tl": "locks bob (id=2)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[7]", "session": null, "sql": null, "fields": { "note": "A now needs bob's row (B has it) — it waits." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[8]", "session": "A", "sql": "UPDATE accounts SET balance = balance + 10 WHERE id = 2", "fields": { "A": "UPDATE accounts SET balance = balance + 10 WHERE id = 2", "blocks": "p1", "tl": "needs bob (id=2)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s", "pending": "UPDATE accounts SET balance = balance + 10 WHERE id = 2" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[9]", "session": null, "sql": null, "fields": { "note": "B now needs alice's row (A has it). A waits for B, B waits for A: a cycle." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\",\"pending\":\"UPDATE accounts SET balance = balance + 10 WHERE id = 2\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s", "pending": "UPDATE accounts SET balance = balance + 10 WHERE id = 2" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[10]", "session": "B", "sql": "UPDATE accounts SET balance = balance + 25 WHERE id = 1", "fields": { "B.fails": "UPDATE accounts SET balance = balance + 25 WHERE id = 1", "error": "40P01", "comment": "deadlock_detected — B is aborted…", "tl": "needs alice (id=1)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\",\"pending\":\"UPDATE accounts SET balance = balance + 10 WHERE id = 2\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s", "pending": "UPDATE accounts SET balance = balance + 10 WHERE id = 2" }, "B": { "phase": "explicit failed (database effects aborted; awaits transaction end)", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[11]", "session": null, "sql": null, "fields": { "note": "The victim's abort frees bob's row, so A's stuck UPDATE completes." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\",\"pending\":\"UPDATE accounts SET balance = balance + 10 WHERE id = 2\"}; B={\"phase\":\"explicit failed (database effects aborted; awaits transaction end)\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s", "pending": "UPDATE accounts SET balance = balance + 10 WHERE id = 2" }, "B": { "phase": "explicit failed (database effects aborted; awaits transaction end)", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[12]", "session": "A", "sql": "UPDATE accounts SET balance = balance + 10 WHERE id = 2", "fields": { "success": "p1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\",\"pending\":\"UPDATE accounts SET balance = balance + 10 WHERE id = 2\"}; B={\"phase\":\"explicit failed (database effects aborted; awaits transaction end)\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "explicit failed (database effects aborted; awaits transaction end)", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[13]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"explicit failed (database effects aborted; awaits transaction end)\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "explicit failed (database effects aborted; awaits transaction end)", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[14]", "session": "B", "sql": "ROLLBACK", "fields": { "B": "ROLLBACK" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"explicit failed (database effects aborted; awaits transaction end)\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } }, { "occurrence": "scenarios/postgres/03-locking/deadlock.yaml#steps[15]", "session": "A", "sql": "SELECT owner, balance FROM accounts ORDER BY id", "fields": { "A": "SELECT owner, balance FROM accounts ORDER BY id", "expect": [ { "owner": "alice", "balance": 90 }, { "owner": "bob", "balance": 110 } ], "comment": "A's transfer committed; B's database changes did not commit" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"10s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"50ms\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "10s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "50ms" } } } ] } }, "mirrors": [ { "scenario": "scenarios/postgres/03-locking/deadlock.yaml", "transcript": "docs/postgres/03-locking/parts/deadlock.md", "ledger": "docs/public/ledger.jsonl#scenario=postgres/03-locking/deadlock.yaml", "llms": "docs/public/llms-full.txt#section=postgres/03-locking/deadlock.yaml", "metadata": "lead included scenario claim supplies built description/TechArticle where configured" } ] }, { "id": "P17", "path": "scenarios/postgres/03-locking/fk-key-share.yaml", "engine": "PostgreSQL", "observed_version": "18.6", "manual_version": "18", "evidence": { "scenarios": ["scenarios/postgres/03-locking/fk-key-share.yaml"], "official_manual_sections": [ "https://www.postgresql.org/docs/18/explicit-locking.html#LOCKING-ROWS", "https://www.postgresql.org/docs/18/explicit-locking.html#ROW-LOCK-COMPATIBILITY", "https://www.postgresql.org/docs/18/sql-select.html#SQL-FOR-UPDATE-SHARE", "https://github.com/postgres/postgres/blob/REL_18_STABLE/src/backend/utils/adt/ri_triggers.c" ] }, "revisions": { "base": { "sha256": "1b3a3bf492e459ed78f4e1eba726c4b2ab76e5951ea7885228567bb4a8e5746b", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/fk-key-share.yaml#steps[0]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/fk-key-share.yaml#steps[1]", "session": "A", "sql": "INSERT INTO orders VALUES (1, 1)", "fields": { "A": "INSERT INTO orders VALUES (1, 1)", "comment": "FK check locks customers row 1 FOR KEY SHARE", "tl": "INSERT child → FK locks parent FOR KEY SHARE" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/fk-key-share.yaml#steps[2]", "session": null, "sql": null, "fields": { "note": "FOR KEY SHARE doesn't mind non-key updates — B can change the balance." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/fk-key-share.yaml#steps[3]", "session": "B", "sql": "UPDATE customers SET balance = 50 WHERE id = 1", "fields": { "B": "UPDATE customers SET balance = 50 WHERE id = 1", "tl": "UPDATE parent balance → allowed (non-key)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/fk-key-share.yaml#steps[4]", "session": null, "sql": null, "fields": { "note": "But DELETE needs the strongest row lock (FOR UPDATE) — B has to wait." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/fk-key-share.yaml#steps[5]", "session": "B", "sql": "DELETE FROM customers WHERE id = 1", "fields": { "B": "DELETE FROM customers WHERE id = 1", "blocks": "p1", "tl": "DELETE parent → needs FOR UPDATE" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "DELETE FROM customers WHERE id = 1" } } }, { "occurrence": "scenarios/postgres/03-locking/fk-key-share.yaml#steps[6]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "tl": "COMMIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"DELETE FROM customers WHERE id = 1\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "DELETE FROM customers WHERE id = 1" } } }, { "occurrence": "scenarios/postgres/03-locking/fk-key-share.yaml#steps[7]", "session": null, "sql": null, "fields": { "note": "A's order is now committed, so B's DELETE resumes — straight into the FK." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"DELETE FROM customers WHERE id = 1\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "DELETE FROM customers WHERE id = 1" } } }, { "occurrence": "scenarios/postgres/03-locking/fk-key-share.yaml#steps[8]", "session": "B", "sql": "DELETE FROM customers WHERE id = 1", "fields": { "failure": "p1", "error": "23503" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"DELETE FROM customers WHERE id = 1\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/fk-key-share.yaml#steps[9]", "session": "B", "sql": "SELECT balance FROM customers WHERE id = 1", "fields": { "B": "SELECT balance FROM customers WHERE id = 1", "expect": [ { "balance": 50 } ], "comment": "the parent survived, with B's earlier non-key update intact" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] }, "current": { "sha256": "be2b6c367e209147d9cd00fa9918d25718a76827468e8308cbb8760ae6d01bc0", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/fk-key-share.yaml#steps[0]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/fk-key-share.yaml#steps[1]", "session": "A", "sql": "INSERT INTO orders VALUES (1, 1)", "fields": { "A": "INSERT INTO orders VALUES (1, 1)", "comment": "FK check locks customers row 1 FOR KEY SHARE", "tl": "INSERT child → FK locks parent FOR KEY SHARE" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/fk-key-share.yaml#steps[2]", "session": null, "sql": null, "fields": { "note": "FOR KEY SHARE doesn't mind non-key updates — B can change the balance." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/fk-key-share.yaml#steps[3]", "session": "B", "sql": "UPDATE customers SET balance = 50 WHERE id = 1", "fields": { "B": "UPDATE customers SET balance = 50 WHERE id = 1", "tl": "UPDATE parent balance → allowed (non-key)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/fk-key-share.yaml#steps[4]", "session": null, "sql": null, "fields": { "note": "But DELETE needs the strongest row lock (FOR UPDATE) — B has to wait." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/fk-key-share.yaml#steps[5]", "session": "B", "sql": "DELETE FROM customers WHERE id = 1", "fields": { "B": "DELETE FROM customers WHERE id = 1", "blocks": "p1", "tl": "DELETE parent → needs FOR UPDATE" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "DELETE FROM customers WHERE id = 1" } } }, { "occurrence": "scenarios/postgres/03-locking/fk-key-share.yaml#steps[6]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "tl": "COMMIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"DELETE FROM customers WHERE id = 1\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "DELETE FROM customers WHERE id = 1" } } }, { "occurrence": "scenarios/postgres/03-locking/fk-key-share.yaml#steps[7]", "session": null, "sql": null, "fields": { "note": "A's order is now committed, so B's DELETE resumes — straight into the FK." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"DELETE FROM customers WHERE id = 1\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "DELETE FROM customers WHERE id = 1" } } }, { "occurrence": "scenarios/postgres/03-locking/fk-key-share.yaml#steps[8]", "session": "B", "sql": "DELETE FROM customers WHERE id = 1", "fields": { "failure": "p1", "error": "23503" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"DELETE FROM customers WHERE id = 1\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/fk-key-share.yaml#steps[9]", "session": "B", "sql": "SELECT balance FROM customers WHERE id = 1", "fields": { "B": "SELECT balance FROM customers WHERE id = 1", "expect": [ { "balance": 50 } ], "comment": "the parent survived, with B's earlier non-key update intact" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] } }, "mirrors": [ { "scenario": "scenarios/postgres/03-locking/fk-key-share.yaml", "transcript": "docs/postgres/03-locking/parts/fk-key-share.md", "ledger": "docs/public/ledger.jsonl#scenario=postgres/03-locking/fk-key-share.yaml", "llms": "docs/public/llms-full.txt#section=postgres/03-locking/fk-key-share.yaml", "metadata": "lead included scenario claim supplies built description/TechArticle where configured" } ] }, { "id": "P18", "path": "scenarios/postgres/03-locking/for-update-blocks.yaml", "engine": "PostgreSQL", "observed_version": "18.6", "manual_version": "18", "evidence": { "scenarios": ["scenarios/postgres/03-locking/for-update-blocks.yaml"], "official_manual_sections": [ "https://www.postgresql.org/docs/18/explicit-locking.html#LOCKING-ROWS", "https://www.postgresql.org/docs/18/explicit-locking.html#ROW-LOCK-COMPATIBILITY", "https://www.postgresql.org/docs/18/sql-select.html#SQL-FOR-UPDATE-SHARE", "https://github.com/postgres/postgres/blob/REL_18_STABLE/src/backend/utils/adt/ri_triggers.c" ] }, "revisions": { "base": { "sha256": "e7ec34c4b4bab1282d70ddc0d3a6cc8fde6211733d17cbcb0ea76932d00cb2e7", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/for-update-blocks.yaml#steps[0]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/for-update-blocks.yaml#steps[1]", "session": "A", "sql": "SELECT * FROM accounts WHERE id = 1 FOR UPDATE", "fields": { "A": "SELECT * FROM accounts WHERE id = 1 FOR UPDATE", "tl": "SELECT … FOR UPDATE (locks the row)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/for-update-blocks.yaml#steps[2]", "session": null, "sql": null, "fields": { "note": "Reading the locked row costs B nothing — MVCC readers don't take row locks." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/for-update-blocks.yaml#steps[3]", "session": "B", "sql": "SELECT balance FROM accounts WHERE id = 1", "fields": { "B": "SELECT balance FROM accounts WHERE id = 1", "expect": [ { "balance": 100 } ], "tl": "SELECT balance → 100 (readers don't block)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/for-update-blocks.yaml#steps[4]", "session": null, "sql": null, "fields": { "note": "Writing to it is another story: B's UPDATE must wait for A." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/for-update-blocks.yaml#steps[5]", "session": "B", "sql": "UPDATE accounts SET balance = balance - 10 WHERE id = 1", "fields": { "B": "UPDATE accounts SET balance = balance - 10 WHERE id = 1", "blocks": "p1", "tl": "UPDATE -10" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance - 10 WHERE id = 1" } } }, { "occurrence": "scenarios/postgres/03-locking/for-update-blocks.yaml#steps[6]", "session": "A", "sql": "UPDATE accounts SET balance = 150 WHERE id = 1", "fields": { "A": "UPDATE accounts SET balance = 150 WHERE id = 1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance - 10 WHERE id = 1\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance - 10 WHERE id = 1" } } }, { "occurrence": "scenarios/postgres/03-locking/for-update-blocks.yaml#steps[7]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "comment": "releases the row lock", "tl": "COMMIT (releases the lock)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance - 10 WHERE id = 1\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance - 10 WHERE id = 1" } } }, { "occurrence": "scenarios/postgres/03-locking/for-update-blocks.yaml#steps[8]", "session": "B", "sql": "UPDATE accounts SET balance = balance - 10 WHERE id = 1", "fields": { "success": "p1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance - 10 WHERE id = 1\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/for-update-blocks.yaml#steps[9]", "session": "B", "sql": "SELECT balance FROM accounts WHERE id = 1", "fields": { "B": "SELECT balance FROM accounts WHERE id = 1", "expect": [ { "balance": 140 } ], "comment": "B's -10 applied on top of A's committed 150" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] }, "current": { "sha256": "8e0f475793c80dcd328a444276d1a079115f70870e99d029e0a025a467fc7250", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/for-update-blocks.yaml#steps[0]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/for-update-blocks.yaml#steps[1]", "session": "A", "sql": "SELECT * FROM accounts WHERE id = 1 FOR UPDATE", "fields": { "A": "SELECT * FROM accounts WHERE id = 1 FOR UPDATE", "tl": "SELECT … FOR UPDATE (locks the row)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/for-update-blocks.yaml#steps[2]", "session": null, "sql": null, "fields": { "note": "B's ordinary SELECT reads the row without a conflicting row-lock request; cost is not measured." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/for-update-blocks.yaml#steps[3]", "session": "B", "sql": "SELECT balance FROM accounts WHERE id = 1", "fields": { "B": "SELECT balance FROM accounts WHERE id = 1", "expect": [ { "balance": 100 } ], "tl": "ordinary SELECT → 100" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/for-update-blocks.yaml#steps[4]", "session": null, "sql": null, "fields": { "note": "Writing to it is another story: B's UPDATE must wait for A." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/for-update-blocks.yaml#steps[5]", "session": "B", "sql": "UPDATE accounts SET balance = balance - 10 WHERE id = 1", "fields": { "B": "UPDATE accounts SET balance = balance - 10 WHERE id = 1", "blocks": "p1", "tl": "UPDATE -10" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance - 10 WHERE id = 1" } } }, { "occurrence": "scenarios/postgres/03-locking/for-update-blocks.yaml#steps[6]", "session": "A", "sql": "UPDATE accounts SET balance = 150 WHERE id = 1", "fields": { "A": "UPDATE accounts SET balance = 150 WHERE id = 1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance - 10 WHERE id = 1\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance - 10 WHERE id = 1" } } }, { "occurrence": "scenarios/postgres/03-locking/for-update-blocks.yaml#steps[7]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "comment": "releases the row lock", "tl": "COMMIT (releases the lock)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance - 10 WHERE id = 1\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance - 10 WHERE id = 1" } } }, { "occurrence": "scenarios/postgres/03-locking/for-update-blocks.yaml#steps[8]", "session": "B", "sql": "UPDATE accounts SET balance = balance - 10 WHERE id = 1", "fields": { "success": "p1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance - 10 WHERE id = 1\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/for-update-blocks.yaml#steps[9]", "session": "B", "sql": "SELECT balance FROM accounts WHERE id = 1", "fields": { "B": "SELECT balance FROM accounts WHERE id = 1", "expect": [ { "balance": 140 } ], "comment": "B's -10 applied on top of A's committed 150" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] } }, "mirrors": [ { "scenario": "scenarios/postgres/03-locking/for-update-blocks.yaml", "transcript": "docs/postgres/03-locking/parts/for-update-blocks.md", "ledger": "docs/public/ledger.jsonl#scenario=postgres/03-locking/for-update-blocks.yaml", "llms": "docs/public/llms-full.txt#section=postgres/03-locking/for-update-blocks.yaml", "metadata": "lead included scenario claim supplies built description/TechArticle where configured" } ] }, { "id": "P19", "path": "scenarios/postgres/03-locking/lock-mode-matrix.yaml", "engine": "PostgreSQL", "observed_version": "18.6", "manual_version": "18", "evidence": { "scenarios": ["scenarios/postgres/03-locking/lock-mode-matrix.yaml"], "official_manual_sections": [ "https://www.postgresql.org/docs/18/explicit-locking.html#LOCKING-ROWS", "https://www.postgresql.org/docs/18/explicit-locking.html#ROW-LOCK-COMPATIBILITY", "https://www.postgresql.org/docs/18/sql-select.html#SQL-FOR-UPDATE-SHARE", "https://github.com/postgres/postgres/blob/REL_18_STABLE/src/backend/utils/adt/ri_triggers.c" ] }, "revisions": { "base": { "sha256": "3ffa874f2f750bcbc9b64873f997658c81a5ad8226699cc6e3ef3eb87dcc6e0d", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[0]", "session": null, "sql": null, "fields": { "note": "Two FOR SHARE locks on the same row coexist happily…" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[1]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[2]", "session": "A", "sql": "SELECT id FROM accounts WHERE id = 1 FOR SHARE", "fields": { "A": "SELECT id FROM accounts WHERE id = 1 FOR SHARE", "tl": "SELECT … FOR SHARE (A)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[3]", "session": "B", "sql": "BEGIN", "fields": { "B": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[4]", "session": "B", "sql": "SELECT id FROM accounts WHERE id = 1 FOR SHARE", "fields": { "B": "SELECT id FROM accounts WHERE id = 1 FOR SHARE", "tl": "SELECT … FOR SHARE (B) → coexists" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[5]", "session": "B", "sql": "COMMIT", "fields": { "B": "COMMIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[6]", "session": null, "sql": null, "fields": { "note": "…but FOR SHARE still blocks a plain UPDATE (which takes FOR NO KEY UPDATE)." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[7]", "session": "B", "sql": "UPDATE accounts SET balance = 200 WHERE id = 1", "fields": { "B": "UPDATE accounts SET balance = 200 WHERE id = 1", "blocks": "p1", "tl": "UPDATE → FOR NO KEY UPDATE" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = 200 WHERE id = 1" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[8]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "tl": "COMMIT (releases A's FOR SHARE)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = 200 WHERE id = 1\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = 200 WHERE id = 1" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[9]", "session": "B", "sql": "UPDATE accounts SET balance = 200 WHERE id = 1", "fields": { "success": "p1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = 200 WHERE id = 1\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[10]", "session": null, "sql": null, "fields": { "note": "The weakest lock, FOR KEY SHARE, even coexists with a running UPDATE…" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[11]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[12]", "session": "A", "sql": "UPDATE accounts SET balance = 300 WHERE id = 1", "fields": { "A": "UPDATE accounts SET balance = 300 WHERE id = 1", "tl": "UPDATE → FOR NO KEY UPDATE (A)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[13]", "session": "B", "sql": "SELECT id FROM accounts WHERE id = 1 FOR KEY SHARE", "fields": { "B": "SELECT id FROM accounts WHERE id = 1 FOR KEY SHARE", "tl": "SELECT … FOR KEY SHARE → coexists with the UPDATE" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[14]", "session": null, "sql": null, "fields": { "note": "…while the strongest, FOR UPDATE, has to wait for it." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[15]", "session": "B", "sql": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE", "fields": { "B": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE", "blocks": "p2", "tl": "SELECT … FOR UPDATE" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[16]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "tl": "COMMIT (releases A)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT id FROM accounts WHERE id = 1 FOR UPDATE\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[17]", "session": "B", "sql": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE", "fields": { "success": "p2" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT id FROM accounts WHERE id = 1 FOR UPDATE\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] }, "current": { "sha256": "b255fb4acb537c54ab22b54719987f6e67916061858ed86bccf899dee6a05cdf", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[0]", "session": null, "sql": null, "fields": { "note": "Two FOR SHARE locks on the same row coexist happily…" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[1]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[2]", "session": "A", "sql": "SELECT id FROM accounts WHERE id = 1 FOR SHARE", "fields": { "A": "SELECT id FROM accounts WHERE id = 1 FOR SHARE", "tl": "SELECT … FOR SHARE (A)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[3]", "session": "B", "sql": "BEGIN", "fields": { "B": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[4]", "session": "B", "sql": "SELECT id FROM accounts WHERE id = 1 FOR SHARE", "fields": { "B": "SELECT id FROM accounts WHERE id = 1 FOR SHARE", "tl": "SELECT … FOR SHARE (B) → coexists" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[5]", "session": "B", "sql": "COMMIT", "fields": { "B": "COMMIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[6]", "session": null, "sql": null, "fields": { "note": "…but FOR SHARE still blocks a plain UPDATE (which takes FOR NO KEY UPDATE)." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[7]", "session": "B", "sql": "UPDATE accounts SET balance = 200 WHERE id = 1", "fields": { "B": "UPDATE accounts SET balance = 200 WHERE id = 1", "blocks": "p1", "tl": "UPDATE → FOR NO KEY UPDATE" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = 200 WHERE id = 1" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[8]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "tl": "COMMIT (releases A's FOR SHARE)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = 200 WHERE id = 1\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = 200 WHERE id = 1" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[9]", "session": "B", "sql": "UPDATE accounts SET balance = 200 WHERE id = 1", "fields": { "success": "p1", "affected": 1 }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = 200 WHERE id = 1\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[10]", "session": null, "sql": null, "fields": { "note": "The weakest lock, FOR KEY SHARE, even coexists with a running UPDATE…" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[11]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[12]", "session": "A", "sql": "UPDATE accounts SET balance = 300 WHERE id = 1", "fields": { "A": "UPDATE accounts SET balance = 300 WHERE id = 1", "tl": "UPDATE → FOR NO KEY UPDATE (A)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[13]", "session": "B", "sql": "SELECT id FROM accounts WHERE id = 1 FOR KEY SHARE", "fields": { "B": "SELECT id FROM accounts WHERE id = 1 FOR KEY SHARE", "tl": "SELECT … FOR KEY SHARE → coexists with the UPDATE" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[14]", "session": null, "sql": null, "fields": { "note": "…while the strongest, FOR UPDATE, has to wait for it." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[15]", "session": "B", "sql": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE", "fields": { "B": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE", "blocks": "p2", "tl": "SELECT … FOR UPDATE" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[16]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "tl": "COMMIT (releases A)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT id FROM accounts WHERE id = 1 FOR UPDATE\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-mode-matrix.yaml#steps[17]", "session": "B", "sql": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE", "fields": { "success": "p2", "expect": [ { "id": 1 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"SELECT id FROM accounts WHERE id = 1 FOR UPDATE\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] } }, "mirrors": [ { "scenario": "scenarios/postgres/03-locking/lock-mode-matrix.yaml", "transcript": "docs/postgres/03-locking/parts/lock-mode-matrix.md", "ledger": "docs/public/ledger.jsonl#scenario=postgres/03-locking/lock-mode-matrix.yaml", "llms": "docs/public/llms-full.txt#section=postgres/03-locking/lock-mode-matrix.yaml", "metadata": "lead included scenario claim supplies built description/TechArticle where configured" } ] }, { "id": "P20", "path": "scenarios/postgres/03-locking/lock-queue-fifo.yaml", "engine": "PostgreSQL", "observed_version": "18.6", "manual_version": "18", "evidence": { "scenarios": ["scenarios/postgres/03-locking/lock-queue-fifo.yaml"], "official_manual_sections": [ "https://www.postgresql.org/docs/18/functions-info.html#FUNCTIONS-INFO-SESSION", "https://www.postgresql.org/docs/18/view-pg-locks.html" ] }, "revisions": { "base": { "sha256": "ed2ff5e4ee730da008c45204499dd0d132a19f2ba2cfd4a148161bb93c28390d", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[0]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[1]", "session": "A", "sql": "UPDATE accounts SET balance = balance + 1 WHERE id = 1", "fields": { "A": "UPDATE accounts SET balance = balance + 1 WHERE id = 1", "tl": "UPDATE +1 (takes the row lock)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[2]", "session": "B", "sql": "BEGIN", "fields": { "B": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[3]", "session": "B", "sql": "UPDATE accounts SET balance = balance + 10 WHERE id = 1", "fields": { "B": "UPDATE accounts SET balance = balance + 10 WHERE id = 1", "blocks": "p1", "tl": "UPDATE +10" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 10 WHERE id = 1" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[4]", "session": "C", "sql": "UPDATE accounts SET balance = balance + 100 WHERE id = 1", "fields": { "C": "UPDATE accounts SET balance = balance + 100 WHERE id = 1", "blocks": "p2", "tl": "UPDATE +100" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 10 WHERE id = 1\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 10 WHERE id = 1" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 100 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[5]", "session": null, "sql": null, "fields": { "note": "A fourth session, M, can watch the pile-up in pg_stat_activity." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 10 WHERE id = 1\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 100 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 10 WHERE id = 1" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 100 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[6]", "session": "M", "sql": "SELECT application_name AS waiting, pg_blocking_pids(pid) AS blocked_by\nFROM pg_stat_activity\nWHERE wait_event_type = 'Lock'\nORDER BY application_name\n", "fields": { "M": "SELECT application_name AS waiting, pg_blocking_pids(pid) AS blocked_by\nFROM pg_stat_activity\nWHERE wait_event_type = 'Lock'\nORDER BY application_name\n", "expect": [ { "waiting": "B" }, { "waiting": "C" } ], "tl": "who's waiting? → B and C" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 10 WHERE id = 1\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 100 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 10 WHERE id = 1" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 100 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[7]", "session": null, "sql": null, "fields": { "note": "A commits. The lock goes to B — the head of the queue — not to C." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 10 WHERE id = 1\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 100 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 10 WHERE id = 1" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 100 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[8]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "tl": "COMMIT → lock passes to B" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 10 WHERE id = 1\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 100 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 10 WHERE id = 1" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 100 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[9]", "session": "B", "sql": "UPDATE accounts SET balance = balance + 10 WHERE id = 1", "fields": { "success": "p1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 10 WHERE id = 1\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 100 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 100 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[10]", "session": null, "sql": null, "fields": { "locked": "C" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 100 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 100 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[11]", "session": "M", "sql": "SELECT application_name AS waiting, pg_blocking_pids(pid) AS blocked_by\nFROM pg_stat_activity\nWHERE wait_event_type = 'Lock'\nORDER BY application_name\n", "fields": { "M": "SELECT application_name AS waiting, pg_blocking_pids(pid) AS blocked_by\nFROM pg_stat_activity\nWHERE wait_event_type = 'Lock'\nORDER BY application_name\n", "expect": [ { "waiting": "C" } ], "comment": "C is still in line, now behind B" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 100 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 100 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[12]", "session": "B", "sql": "COMMIT", "fields": { "B": "COMMIT", "tl": "COMMIT → lock passes to C" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 100 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 100 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[13]", "session": "C", "sql": "UPDATE accounts SET balance = balance + 100 WHERE id = 1", "fields": { "success": "p2" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 100 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[14]", "session": "C", "sql": "SELECT balance FROM accounts WHERE id = 1", "fields": { "C": "SELECT balance FROM accounts WHERE id = 1", "expect": [ { "balance": 211 } ], "comment": "100 + 1 + 10 + 100 — every update landed, in queue order" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] }, "current": { "sha256": "c91477412ef25683982f04dcdad86b2a6062176c385967756472239d9b99bf78", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[0]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[1]", "session": "A", "sql": "UPDATE accounts SET balance = balance + 1 WHERE id = 1", "fields": { "A": "UPDATE accounts SET balance = balance + 1 WHERE id = 1", "tl": "UPDATE +1 (takes the row lock)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[2]", "session": "B", "sql": "BEGIN", "fields": { "B": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[3]", "session": "B", "sql": "UPDATE accounts SET balance = balance + 10 WHERE id = 1", "fields": { "B": "UPDATE accounts SET balance = balance + 10 WHERE id = 1", "blocks": "p1", "tl": "UPDATE +10" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 10 WHERE id = 1" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[4]", "session": "C", "sql": "UPDATE accounts SET balance = balance + 100 WHERE id = 1", "fields": { "C": "UPDATE accounts SET balance = balance + 100 WHERE id = 1", "blocks": "p2", "tl": "UPDATE +100" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 10 WHERE id = 1\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 10 WHERE id = 1" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 100 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[5]", "session": null, "sql": null, "fields": { "note": "A fourth session, M, can watch the pile-up in pg_stat_activity." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 10 WHERE id = 1\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 100 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 10 WHERE id = 1" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 100 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[6]", "session": "M", "sql": "SELECT application_name AS waiting, pg_blocking_pids(pid) AS blocked_by\nFROM pg_stat_activity\nWHERE wait_event_type = 'Lock'\nORDER BY application_name\n", "fields": { "M": "SELECT application_name AS waiting, pg_blocking_pids(pid) AS blocked_by\nFROM pg_stat_activity\nWHERE wait_event_type = 'Lock'\nORDER BY application_name\n", "expect": [ { "waiting": "B" }, { "waiting": "C" } ], "tl": "who's waiting? → B and C" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 10 WHERE id = 1\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 100 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 10 WHERE id = 1" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 100 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[7]", "session": null, "sql": null, "fields": { "note": "A commits. B completes while C is observed waiting again." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 10 WHERE id = 1\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 100 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 10 WHERE id = 1" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 100 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[8]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "tl": "COMMIT → lock passes to B" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 10 WHERE id = 1\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 100 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 10 WHERE id = 1" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 100 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[9]", "session": "B", "sql": "UPDATE accounts SET balance = balance + 10 WHERE id = 1", "fields": { "success": "p1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 10 WHERE id = 1\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 100 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 100 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[10]", "session": null, "sql": null, "fields": { "locked": "C" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 100 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 100 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[11]", "session": "M", "sql": "SELECT application_name AS waiting, pg_blocking_pids(pid) AS blocked_by\nFROM pg_stat_activity\nWHERE wait_event_type = 'Lock'\nORDER BY application_name\n", "fields": { "M": "SELECT application_name AS waiting, pg_blocking_pids(pid) AS blocked_by\nFROM pg_stat_activity\nWHERE wait_event_type = 'Lock'\nORDER BY application_name\n", "expect": [ { "waiting": "C" } ], "comment": "C is still in line, now behind B" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 100 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 100 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[12]", "session": "B", "sql": "COMMIT", "fields": { "B": "COMMIT", "tl": "COMMIT → lock passes to C" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 100 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = balance + 100 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[13]", "session": "C", "sql": "UPDATE accounts SET balance = balance + 100 WHERE id = 1", "fields": { "success": "p2" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = balance + 100 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-queue-fifo.yaml#steps[14]", "session": "C", "sql": "SELECT balance FROM accounts WHERE id = 1", "fields": { "C": "SELECT balance FROM accounts WHERE id = 1", "expect": [ { "balance": 211 } ], "comment": "100 + 1 + 10 + 100 — every update landed, in queue order" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] } }, "mirrors": [ { "scenario": "scenarios/postgres/03-locking/lock-queue-fifo.yaml", "transcript": "docs/postgres/03-locking/parts/lock-queue-fifo.md", "ledger": "docs/public/ledger.jsonl#scenario=postgres/03-locking/lock-queue-fifo.yaml", "llms": "docs/public/llms-full.txt#section=postgres/03-locking/lock-queue-fifo.yaml", "metadata": "lead included scenario claim supplies built description/TechArticle where configured" } ] }, { "id": "P21", "path": "scenarios/postgres/03-locking/lock-timeout.yaml", "engine": "PostgreSQL", "observed_version": "18.6", "manual_version": "18", "evidence": { "scenarios": ["scenarios/postgres/03-locking/lock-timeout.yaml"], "official_manual_sections": [ "https://www.postgresql.org/docs/18/sql-select.html#SQL-FOR-UPDATE-SHARE", "https://www.postgresql.org/docs/18/runtime-config-client.html#GUC-LOCK-TIMEOUT", "https://www.postgresql.org/docs/18/sql-rollback.html", "https://www.postgresql.org/docs/18/sql-rollback-to.html" ] }, "revisions": { "base": { "sha256": "58eedd7bba68a4ee439feea4351d439ad6f3a177f9a66b0fc5ca7d0d2d5a90d5", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/lock-timeout.yaml#steps[0]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-timeout.yaml#steps[1]", "session": "A", "sql": "UPDATE accounts SET balance = 200 WHERE id = 1", "fields": { "A": "UPDATE accounts SET balance = 200 WHERE id = 1", "tl": "UPDATE 200 (locks row 1)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-timeout.yaml#steps[2]", "session": "B", "sql": "SET lock_timeout = '100ms'", "fields": { "B": "SET lock_timeout = '100ms'" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-timeout.yaml#steps[3]", "session": null, "sql": null, "fields": { "note": "B queues for the row lock like anyone else — but gives up after 100ms." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-timeout.yaml#steps[4]", "session": "B", "sql": "UPDATE accounts SET balance = 300 WHERE id = 1", "fields": { "B.fails": "UPDATE accounts SET balance = 300 WHERE id = 1", "error": "55P03", "comment": "lock_not_available, raised after the timeout", "tl": "UPDATE 300 → gives up after 100ms" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-timeout.yaml#steps[5]", "session": null, "sql": null, "fields": { "note": "The failure canceled only B's statement — a retry after A commits works." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-timeout.yaml#steps[6]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "tl": "COMMIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-timeout.yaml#steps[7]", "session": "B", "sql": "UPDATE accounts SET balance = 300 WHERE id = 1", "fields": { "B": "UPDATE accounts SET balance = 300 WHERE id = 1", "tl": "UPDATE 300 (retry succeeds)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-timeout.yaml#steps[8]", "session": "B", "sql": "SELECT balance FROM accounts WHERE id = 1", "fields": { "B": "SELECT balance FROM accounts WHERE id = 1", "expect": [ { "balance": 300 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" } } } ] }, "current": { "sha256": "a9dfa662cf646ace0fed682f3d2c308920534ce4f2c6f1b6e78e0d49ee17c468", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/lock-timeout.yaml#steps[0]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-timeout.yaml#steps[1]", "session": "A", "sql": "UPDATE accounts SET balance = 200 WHERE id = 1", "fields": { "A": "UPDATE accounts SET balance = 200 WHERE id = 1", "tl": "UPDATE 200 (locks row 1)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-timeout.yaml#steps[2]", "session": "B", "sql": "SET lock_timeout = '100ms'", "fields": { "B": "SET lock_timeout = '100ms'" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-timeout.yaml#steps[3]", "session": null, "sql": null, "fields": { "note": "B queues for the row lock like anyone else — but gives up after 100ms." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-timeout.yaml#steps[4]", "session": "B", "sql": "UPDATE accounts SET balance = 300 WHERE id = 1", "fields": { "B.fails": "UPDATE accounts SET balance = 300 WHERE id = 1", "error": "55P03", "comment": "lock_not_available, raised after the timeout", "tl": "UPDATE 300 → gives up after 100ms" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-timeout.yaml#steps[5]", "session": null, "sql": null, "fields": { "note": "B's failed standalone statement ends its implicit transaction; a fresh attempt after A commits works here." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-timeout.yaml#steps[6]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "tl": "COMMIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-timeout.yaml#steps[7]", "session": "B", "sql": "UPDATE accounts SET balance = 300 WHERE id = 1", "fields": { "B": "UPDATE accounts SET balance = 300 WHERE id = 1", "tl": "UPDATE 300 (retry succeeds)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/lock-timeout.yaml#steps[8]", "session": "B", "sql": "SELECT balance FROM accounts WHERE id = 1", "fields": { "B": "SELECT balance FROM accounts WHERE id = 1", "expect": [ { "balance": 300 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"100ms\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "100ms", "deadlock_timeout": "1s" } } } ] } }, "mirrors": [ { "scenario": "scenarios/postgres/03-locking/lock-timeout.yaml", "transcript": "docs/postgres/03-locking/parts/lock-timeout.md", "ledger": "docs/public/ledger.jsonl#scenario=postgres/03-locking/lock-timeout.yaml", "llms": "docs/public/llms-full.txt#section=postgres/03-locking/lock-timeout.yaml", "metadata": "lead included scenario claim supplies built description/TechArticle where configured" } ] }, { "id": "P22", "path": "scenarios/postgres/03-locking/monitoring-locks.yaml", "engine": "PostgreSQL", "observed_version": "18.6", "manual_version": "18", "evidence": { "scenarios": ["scenarios/postgres/03-locking/monitoring-locks.yaml"], "official_manual_sections": [ "https://www.postgresql.org/docs/18/view-pg-locks.html", "https://www.postgresql.org/docs/18/monitoring-stats.html#MONITORING-PG-STAT-ACTIVITY-VIEW", "https://www.postgresql.org/docs/18/functions-info.html#FUNCTIONS-INFO-SESSION" ] }, "revisions": { "base": { "sha256": "7968ddf364ff22667782b393cbf8c0245d454a9ac1d085b3f122da458c82145f", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[0]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[1]", "session": "A", "sql": "UPDATE accounts SET balance = 200 WHERE id = 1", "fields": { "A": "UPDATE accounts SET balance = 200 WHERE id = 1", "tl": "UPDATE (takes the row lock)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[2]", "session": null, "sql": null, "fields": { "note": "One innocent UPDATE = four locks: table, index, its own xid, its own virtual xid." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[3]", "session": "M", "sql": "SELECT l.locktype, l.relation::regclass AS relation, l.mode, l.granted\nFROM pg_locks l JOIN pg_stat_activity a ON a.pid = l.pid\nWHERE a.application_name = 'A'\nORDER BY l.locktype, l.relation::regclass::text, l.mode\n", "fields": { "M": "SELECT l.locktype, l.relation::regclass AS relation, l.mode, l.granted\nFROM pg_locks l JOIN pg_stat_activity a ON a.pid = l.pid\nWHERE a.application_name = 'A'\nORDER BY l.locktype, l.relation::regclass::text, l.mode\n", "expect": [ { "locktype": "relation", "relation": "accounts", "mode": "RowExclusiveLock", "granted": true }, { "locktype": "relation", "relation": "accounts_pkey", "mode": "RowExclusiveLock", "granted": true }, { "locktype": "transactionid", "relation": null, "mode": "ExclusiveLock", "granted": true }, { "locktype": "virtualxid", "relation": null, "mode": "ExclusiveLock", "granted": true } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[4]", "session": "B", "sql": "UPDATE accounts SET balance = 300 WHERE id = 1", "fields": { "B": "UPDATE accounts SET balance = 300 WHERE id = 1", "blocks": "p1", "tl": "UPDATE → waits on A" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = 300 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[5]", "session": null, "sql": null, "fields": { "note": "The waiter's tell: a lock row with granted = f — it wants A's transaction id." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = 300 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = 300 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[6]", "session": "M", "sql": "SELECT l.locktype, l.mode, l.granted\nFROM pg_locks l JOIN pg_stat_activity a ON a.pid = l.pid\nWHERE a.application_name = 'B' AND NOT l.granted\n", "fields": { "M": "SELECT l.locktype, l.mode, l.granted\nFROM pg_locks l JOIN pg_stat_activity a ON a.pid = l.pid\nWHERE a.application_name = 'B' AND NOT l.granted\n", "expect": [ { "locktype": "transactionid", "mode": "ShareLock", "granted": false } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = 300 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = 300 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[7]", "session": null, "sql": null, "fields": { "note": "You rarely need to decode pg_locks by hand — pg_blocking_pids() names the culprit." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = 300 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = 300 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[8]", "session": "M", "sql": "SELECT waiter.application_name AS waiter, blocker.application_name AS blocker\nFROM pg_stat_activity waiter\nJOIN pg_stat_activity blocker ON blocker.pid = ANY (pg_blocking_pids(waiter.pid))\nWHERE waiter.wait_event_type = 'Lock'\nORDER BY waiter.application_name, blocker.application_name\n", "fields": { "M": "SELECT waiter.application_name AS waiter, blocker.application_name AS blocker\nFROM pg_stat_activity waiter\nJOIN pg_stat_activity blocker ON blocker.pid = ANY (pg_blocking_pids(waiter.pid))\nWHERE waiter.wait_event_type = 'Lock'\nORDER BY waiter.application_name, blocker.application_name\n", "expect": [ { "waiter": "B", "blocker": "A" } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = 300 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = 300 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[9]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "tl": "COMMIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = 300 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = 300 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[10]", "session": "B", "sql": "UPDATE accounts SET balance = 300 WHERE id = 1", "fields": { "success": "p1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = 300 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] }, "current": { "sha256": "5eea52c84fc712dcbf404558bbbff9f49634c2a4964ac8c123e5e64ade371fbe", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[0]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[1]", "session": "A", "sql": "UPDATE accounts SET balance = 200 WHERE id = 1", "fields": { "A": "UPDATE accounts SET balance = 200 WHERE id = 1", "tl": "UPDATE (takes the row lock)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[2]", "session": null, "sql": null, "fields": { "note": "This UPDATE's inspected lock entries: table, index, assigned xid and virtual xid." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[3]", "session": "M", "sql": "SELECT l.locktype, l.relation::regclass AS relation, l.mode, l.granted\nFROM pg_locks l JOIN pg_stat_activity a ON a.pid = l.pid\nWHERE a.application_name = 'A'\nORDER BY l.locktype, l.relation::regclass::text, l.mode\n", "fields": { "M": "SELECT l.locktype, l.relation::regclass AS relation, l.mode, l.granted\nFROM pg_locks l JOIN pg_stat_activity a ON a.pid = l.pid\nWHERE a.application_name = 'A'\nORDER BY l.locktype, l.relation::regclass::text, l.mode\n", "expect": [ { "locktype": "relation", "relation": "accounts", "mode": "RowExclusiveLock", "granted": true }, { "locktype": "relation", "relation": "accounts_pkey", "mode": "RowExclusiveLock", "granted": true }, { "locktype": "transactionid", "relation": null, "mode": "ExclusiveLock", "granted": true }, { "locktype": "virtualxid", "relation": null, "mode": "ExclusiveLock", "granted": true } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[4]", "session": "B", "sql": "UPDATE accounts SET balance = 300 WHERE id = 1", "fields": { "B": "UPDATE accounts SET balance = 300 WHERE id = 1", "blocks": "p1", "tl": "UPDATE → waits on A" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = 300 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[5]", "session": null, "sql": null, "fields": { "note": "The waiter's tell: a lock row with granted = f — it wants A's transaction id." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = 300 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = 300 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[6]", "session": "M", "sql": "SELECT l.locktype, l.mode, l.granted\nFROM pg_locks l JOIN pg_stat_activity a ON a.pid = l.pid\nWHERE a.application_name = 'B' AND NOT l.granted\n", "fields": { "M": "SELECT l.locktype, l.mode, l.granted\nFROM pg_locks l JOIN pg_stat_activity a ON a.pid = l.pid\nWHERE a.application_name = 'B' AND NOT l.granted\n", "expect": [ { "locktype": "transactionid", "mode": "ShareLock", "granted": false } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = 300 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = 300 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[7]", "session": null, "sql": null, "fields": { "note": "You rarely need to decode pg_locks by hand — pg_blocking_pids() names the culprit." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = 300 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = 300 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[8]", "session": "M", "sql": "SELECT waiter.application_name AS waiter, blocker.application_name AS blocker\nFROM pg_stat_activity waiter\nJOIN pg_stat_activity blocker ON blocker.pid = ANY (pg_blocking_pids(waiter.pid))\nWHERE waiter.wait_event_type = 'Lock'\nORDER BY waiter.application_name, blocker.application_name\n", "fields": { "M": "SELECT waiter.application_name AS waiter, blocker.application_name AS blocker\nFROM pg_stat_activity waiter\nJOIN pg_stat_activity blocker ON blocker.pid = ANY (pg_blocking_pids(waiter.pid))\nWHERE waiter.wait_event_type = 'Lock'\nORDER BY waiter.application_name, blocker.application_name\n", "expect": [ { "waiter": "B", "blocker": "A" } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = 300 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = 300 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[9]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "tl": "COMMIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = 300 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "implicit active pending", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s", "pending": "UPDATE accounts SET balance = 300 WHERE id = 1" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/monitoring-locks.yaml#steps[10]", "session": "B", "sql": "UPDATE accounts SET balance = 300 WHERE id = 1", "fields": { "success": "p1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"implicit active pending\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\",\"pending\":\"UPDATE accounts SET balance = 300 WHERE id = 1\"}; M={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "M": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] } }, "mirrors": [ { "scenario": "scenarios/postgres/03-locking/monitoring-locks.yaml", "transcript": "docs/postgres/03-locking/parts/monitoring-locks.md", "ledger": "docs/public/ledger.jsonl#scenario=postgres/03-locking/monitoring-locks.yaml", "llms": "docs/public/llms-full.txt#section=postgres/03-locking/monitoring-locks.yaml", "metadata": "lead included scenario claim supplies built description/TechArticle where configured" } ] }, { "id": "P23", "path": "scenarios/postgres/03-locking/nowait.yaml", "engine": "PostgreSQL", "observed_version": "18.6", "manual_version": "18", "evidence": { "scenarios": ["scenarios/postgres/03-locking/nowait.yaml"], "official_manual_sections": [ "https://www.postgresql.org/docs/18/sql-select.html#SQL-FOR-UPDATE-SHARE", "https://www.postgresql.org/docs/18/runtime-config-client.html#GUC-LOCK-TIMEOUT", "https://www.postgresql.org/docs/18/sql-rollback.html", "https://www.postgresql.org/docs/18/sql-rollback-to.html" ] }, "revisions": { "base": { "sha256": "15f93408e3180097d7e17e92b8f3c69a014beb8b4fc9ac0a25dd2ccf1ae3b704", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/nowait.yaml#steps[0]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/nowait.yaml#steps[1]", "session": "A", "sql": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE", "fields": { "A": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE", "tl": "SELECT … FOR UPDATE (locks row 1)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/nowait.yaml#steps[2]", "session": "B", "sql": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE NOWAIT", "fields": { "B.fails": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE NOWAIT", "error": "55P03", "comment": "lock_not_available — instantly, no waiting", "tl": "… FOR UPDATE NOWAIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/nowait.yaml#steps[3]", "session": null, "sql": null, "fields": { "note": "Once A is done, the same statement succeeds." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/nowait.yaml#steps[4]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "tl": "COMMIT (releases the lock)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/nowait.yaml#steps[5]", "session": "B", "sql": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE NOWAIT", "fields": { "B": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE NOWAIT", "expect": [ { "id": 1 } ], "tl": "… NOWAIT → row 1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] }, "current": { "sha256": "7338e8a76ee61d0f202c303a5a6606e3397dc84b68f574af5c693b663d1d4ee5", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/nowait.yaml#steps[0]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/nowait.yaml#steps[1]", "session": "A", "sql": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE", "fields": { "A": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE", "tl": "SELECT … FOR UPDATE (locks row 1)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/nowait.yaml#steps[2]", "session": "B", "sql": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE NOWAIT", "fields": { "B.fails": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE NOWAIT", "error": "55P03", "comment": "lock_not_available from the conflicting row-lock request", "tl": "… FOR UPDATE NOWAIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/nowait.yaml#steps[3]", "session": null, "sql": null, "fields": { "note": "Once A is done, the same statement succeeds." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/nowait.yaml#steps[4]", "session": "A", "sql": "COMMIT", "fields": { "A": "COMMIT", "tl": "COMMIT (releases the lock)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/nowait.yaml#steps[5]", "session": "B", "sql": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE NOWAIT", "fields": { "B": "SELECT id FROM accounts WHERE id = 1 FOR UPDATE NOWAIT", "expect": [ { "id": 1 } ], "tl": "… NOWAIT → row 1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] } }, "mirrors": [ { "scenario": "scenarios/postgres/03-locking/nowait.yaml", "transcript": "docs/postgres/03-locking/parts/nowait.md", "ledger": "docs/public/ledger.jsonl#scenario=postgres/03-locking/nowait.yaml", "llms": "docs/public/llms-full.txt#section=postgres/03-locking/nowait.yaml", "metadata": "lead included scenario claim supplies built description/TechArticle where configured" } ] }, { "id": "P24", "path": "scenarios/postgres/03-locking/skip-locked.yaml", "engine": "PostgreSQL", "observed_version": "18.6", "manual_version": "18", "evidence": { "scenarios": ["scenarios/postgres/03-locking/skip-locked.yaml"], "official_manual_sections": [ "https://www.postgresql.org/docs/18/sql-select.html#SQL-FOR-UPDATE-SHARE", "https://www.postgresql.org/docs/18/runtime-config-client.html#GUC-LOCK-TIMEOUT", "https://www.postgresql.org/docs/18/sql-rollback.html", "https://www.postgresql.org/docs/18/sql-rollback-to.html" ] }, "revisions": { "base": { "sha256": "c5a6d8a5b0464801647729e9e84d34d5091211f64f4941e07829d909f6adffc4", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[0]", "session": null, "sql": null, "fields": { "note": "Four workers run the exact same query at the same time." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[1]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[2]", "session": "A", "sql": "SELECT * FROM jobs ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED", "fields": { "A": "SELECT * FROM jobs ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED", "expect": [ { "id": 1 } ], "tl": "SKIP LOCKED → job 1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[3]", "session": "B", "sql": "BEGIN", "fields": { "B": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[4]", "session": "B", "sql": "SELECT * FROM jobs ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED", "fields": { "B": "SELECT * FROM jobs ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED", "expect": [ { "id": 2 } ], "comment": "job 1 is locked by A — skipped, no waiting", "tl": "SKIP LOCKED → job 2 (skips 1)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[5]", "session": "C", "sql": "BEGIN", "fields": { "C": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[6]", "session": "C", "sql": "SELECT * FROM jobs ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED", "fields": { "C": "SELECT * FROM jobs ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED", "expect": [ { "id": 3 } ], "tl": "SKIP LOCKED → job 3 (skips 1, 2)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[7]", "session": null, "sql": null, "fields": { "note": "Worker D finds the queue empty — an instant answer, not a wait." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[8]", "session": "D", "sql": "SELECT * FROM jobs ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED", "fields": { "D": "SELECT * FROM jobs ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED", "expect": [], "tl": "SKIP LOCKED → nothing free" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[9]", "session": null, "sql": null, "fields": { "note": "A worker crash (rollback) puts its job straight back on the queue." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[10]", "session": "A", "sql": "ROLLBACK", "fields": { "A": "ROLLBACK", "tl": "ROLLBACK → job 1 back on the queue" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[11]", "session": "D", "sql": "SELECT * FROM jobs ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED", "fields": { "D": "SELECT * FROM jobs ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED", "expect": [ { "id": 1 } ], "tl": "SKIP LOCKED → job 1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[12]", "session": "B", "sql": "COMMIT", "fields": { "B": "COMMIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[13]", "session": "C", "sql": "COMMIT", "fields": { "C": "COMMIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] }, "current": { "sha256": "3f4789cd78289b0d51a8bb45547d9eba1bc7b49304bef7f448f5a9e56064ecc2", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[0]", "session": null, "sql": null, "fields": { "note": "Four sessions run the same query in the listed order with overlapping transactions." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[1]", "session": "A", "sql": "BEGIN", "fields": { "A": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[2]", "session": "A", "sql": "SELECT * FROM jobs ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED", "fields": { "A": "SELECT * FROM jobs ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED", "expect": [ { "id": 1 } ], "tl": "SKIP LOCKED → job 1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[3]", "session": "B", "sql": "BEGIN", "fields": { "B": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[4]", "session": "B", "sql": "SELECT * FROM jobs ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED", "fields": { "B": "SELECT * FROM jobs ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED", "expect": [ { "id": 2 } ], "comment": "job 1 is locked by A — skipped, no waiting", "tl": "SKIP LOCKED → job 2 (skips 1)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[5]", "session": "C", "sql": "BEGIN", "fields": { "C": "BEGIN" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[6]", "session": "C", "sql": "SELECT * FROM jobs ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED", "fields": { "C": "SELECT * FROM jobs ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED", "expect": [ { "id": 3 } ], "tl": "SKIP LOCKED → job 3 (skips 1, 2)" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[7]", "session": null, "sql": null, "fields": { "note": "D finds no lockable row in this query; three rows still exist." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[8]", "session": "D", "sql": "SELECT * FROM jobs ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED", "fields": { "D": "SELECT * FROM jobs ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED", "expect": [], "tl": "SKIP LOCKED → nothing free" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[9]", "session": null, "sql": null, "fields": { "note": "Explicit ROLLBACK releases A's row lock; a process crash is not injected." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[10]", "session": "A", "sql": "ROLLBACK", "fields": { "A": "ROLLBACK", "tl": "ROLLBACK → job 1 back on the queue" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[11]", "session": "D", "sql": "SELECT * FROM jobs ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED", "fields": { "D": "SELECT * FROM jobs ORDER BY id LIMIT 1 FOR UPDATE SKIP LOCKED", "expect": [ { "id": 1 } ], "tl": "SKIP LOCKED → job 1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[12]", "session": "B", "sql": "COMMIT", "fields": { "B": "COMMIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/03-locking/skip-locked.yaml#steps[13]", "session": "C", "sql": "COMMIT", "fields": { "C": "COMMIT" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; D={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "D": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] } }, "mirrors": [ { "scenario": "scenarios/postgres/03-locking/skip-locked.yaml", "transcript": "docs/postgres/03-locking/parts/skip-locked.md", "ledger": "docs/public/ledger.jsonl#scenario=postgres/03-locking/skip-locked.yaml", "llms": "docs/public/llms-full.txt#section=postgres/03-locking/skip-locked.yaml", "metadata": "lead included scenario claim supplies built description/TechArticle where configured" } ] }, { "id": "P25", "path": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml", "engine": "PostgreSQL", "observed_version": "18.6", "manual_version": "18", "evidence": { "scenarios": ["scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml"], "official_manual_sections": [ "https://www.postgresql.org/docs/18/routine-vacuuming.html#VACUUM-FOR-SPACE-RECOVERY", "https://www.postgresql.org/docs/18/pageinspect.html", "https://www.postgresql.org/docs/18/monitoring-stats.html#MONITORING-PG-STAT-ALL-TABLES-VIEW", "https://www.postgresql.org/docs/18/storage-hot.html" ] }, "revisions": { "base": { "sha256": "fad256972fbc81e094a9452e106add2ffae554142e702c1ceadbe89b88233b1e", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[0]", "session": "A", "sql": "INSERT INTO counters VALUES (1, 0) RETURNING xmin, n", "fields": { "A": "INSERT INTO counters VALUES (1, 0) RETURNING xmin, n", "capture": "x0" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[1]", "session": null, "sql": null, "fields": { "note": "Three updates to one row. Watch each one get a fresh xid — and leave a corpse." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[2]", "session": "A", "sql": "UPDATE counters SET n = 1 WHERE id = 1 RETURNING xmin, n", "fields": { "A": "UPDATE counters SET n = 1 WHERE id = 1 RETURNING xmin, n", "capture": "x1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[3]", "session": "A", "sql": "UPDATE counters SET n = 2 WHERE id = 1 RETURNING xmin, n", "fields": { "A": "UPDATE counters SET n = 2 WHERE id = 1 RETURNING xmin, n", "capture": "x2" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[4]", "session": "A", "sql": "UPDATE counters SET n = 3 WHERE id = 1 RETURNING xmin, n", "fields": { "A": "UPDATE counters SET n = 3 WHERE id = 1 RETURNING xmin, n", "capture": "x3" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[5]", "session": null, "sql": null, "fields": { "note": "SELECT sees one row. The page holds four tuples — a version chain, three of them dead." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[6]", "session": "A", "sql": "SELECT n FROM counters", "fields": { "A": "SELECT n FROM counters" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[7]", "session": "A", "sql": "SELECT lp, t_xmin, t_xmax, t_ctid\nFROM heap_page_items(get_raw_page('counters', 0)) ORDER BY lp\n", "fields": { "A": "SELECT lp, t_xmin, t_xmax, t_ctid\nFROM heap_page_items(get_raw_page('counters', 0)) ORDER BY lp\n", "expect": [ { "lp": 1, "t_xmin": "${x0.xmin}", "t_xmax": "${x1.xmin}", "t_ctid": "(0,2)" }, { "lp": 2, "t_xmin": "${x1.xmin}", "t_xmax": "${x2.xmin}", "t_ctid": "(0,3)" }, { "lp": 3, "t_xmin": "${x2.xmin}", "t_xmax": "${x3.xmin}", "t_ctid": "(0,4)" }, { "lp": 4, "t_xmin": "${x3.xmin}", "t_xmax": 0, "t_ctid": "(0,4)" } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[8]", "session": null, "sql": null, "fields": { "note": "The same effect at scale: 1000 rows fit in 5 pages of 8 kB." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[9]", "session": "A", "sql": "INSERT INTO bloat SELECT g, 'x' FROM generate_series(1, 1000) g", "fields": { "A": "INSERT INTO bloat SELECT g, 'x' FROM generate_series(1, 1000) g" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[10]", "session": "A", "sql": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "fields": { "A": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "expect": [ { "pages": 5 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[11]", "session": null, "sql": null, "fields": { "note": "One UPDATE of every row = a full second copy of the table." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[12]", "session": "A", "sql": "UPDATE bloat SET filler = 'y'", "fields": { "A": "UPDATE bloat SET filler = 'y'" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[13]", "session": "A", "sql": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "fields": { "A": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "expect": [ { "pages": 9 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[14]", "session": null, "sql": null, "fields": { "note": "Now delete everything. Zero rows — and not a single byte returned." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[15]", "session": "A", "sql": "DELETE FROM bloat", "fields": { "A": "DELETE FROM bloat" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[16]", "session": "A", "sql": "SELECT count(*)::int AS live_rows FROM bloat", "fields": { "A": "SELECT count(*)::int AS live_rows FROM bloat", "expect": [ { "live_rows": 0 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[17]", "session": "A", "sql": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "fields": { "A": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "expect": [ { "pages": 9 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] }, "current": { "sha256": "abb2940c369bba6eed3b614207aa80820c08dfe6f469ed723ed63fa727f199c6", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[0]", "session": "A", "sql": "INSERT INTO counters VALUES (1, 0) RETURNING xmin, n", "fields": { "A": "INSERT INTO counters VALUES (1, 0) RETURNING xmin, n", "capture": "x0" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[1]", "session": null, "sql": null, "fields": { "note": "Three updates to one row. Watch each one get a fresh xid — and leave a corpse." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[2]", "session": "A", "sql": "UPDATE counters SET n = 1 WHERE id = 1 RETURNING xmin, n", "fields": { "A": "UPDATE counters SET n = 1 WHERE id = 1 RETURNING xmin, n", "capture": "x1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[3]", "session": "A", "sql": "UPDATE counters SET n = 2 WHERE id = 1 RETURNING xmin, n", "fields": { "A": "UPDATE counters SET n = 2 WHERE id = 1 RETURNING xmin, n", "capture": "x2" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[4]", "session": "A", "sql": "UPDATE counters SET n = 3 WHERE id = 1 RETURNING xmin, n", "fields": { "A": "UPDATE counters SET n = 3 WHERE id = 1 RETURNING xmin, n", "capture": "x3" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[5]", "session": null, "sql": null, "fields": { "note": "SELECT sees one row. The page holds four tuples — a version chain, three of them dead." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[6]", "session": "A", "sql": "SELECT n FROM counters", "fields": { "A": "SELECT n FROM counters", "expect": [ { "n": 3 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[7]", "session": "A", "sql": "SELECT lp, t_xmin, t_xmax, t_ctid\nFROM heap_page_items(get_raw_page('counters', 0)) ORDER BY lp\n", "fields": { "A": "SELECT lp, t_xmin, t_xmax, t_ctid\nFROM heap_page_items(get_raw_page('counters', 0)) ORDER BY lp\n", "expect": [ { "lp": 1, "t_xmin": "${x0.xmin}", "t_xmax": "${x1.xmin}", "t_ctid": "(0,2)" }, { "lp": 2, "t_xmin": "${x1.xmin}", "t_xmax": "${x2.xmin}", "t_ctid": "(0,3)" }, { "lp": 3, "t_xmin": "${x2.xmin}", "t_xmax": "${x3.xmin}", "t_ctid": "(0,4)" }, { "lp": 4, "t_xmin": "${x3.xmin}", "t_xmax": 0, "t_ctid": "(0,4)" } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[8]", "session": null, "sql": null, "fields": { "note": "The same effect at scale: 1000 rows fit in 5 pages of 8 kB." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[9]", "session": "A", "sql": "INSERT INTO bloat SELECT g, 'x' FROM generate_series(1, 1000) g", "fields": { "A": "INSERT INTO bloat SELECT g, 'x' FROM generate_series(1, 1000) g" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[10]", "session": "A", "sql": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "fields": { "A": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "expect": [ { "pages": 5 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[11]", "session": null, "sql": null, "fields": { "note": "This UPDATE of all 1000 rows grows the heap from 5 to 9 pages, not an exact doubling." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[12]", "session": "A", "sql": "UPDATE bloat SET filler = 'y'", "fields": { "A": "UPDATE bloat SET filler = 'y'" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[13]", "session": "A", "sql": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "fields": { "A": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "expect": [ { "pages": 9 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[14]", "session": null, "sql": null, "fields": { "note": "Now delete everything. Zero rows — and not a single byte returned." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[15]", "session": "A", "sql": "DELETE FROM bloat", "fields": { "A": "DELETE FROM bloat" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[16]", "session": "A", "sql": "SELECT count(*)::int AS live_rows FROM bloat", "fields": { "A": "SELECT count(*)::int AS live_rows FROM bloat", "expect": [ { "live_rows": 0 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml#steps[17]", "session": "A", "sql": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "fields": { "A": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "expect": [ { "pages": 9 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] } }, "mirrors": [ { "scenario": "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml", "transcript": "docs/postgres/04-mvcc/parts/dead-tuples-and-bloat.md", "ledger": "docs/public/ledger.jsonl#scenario=postgres/04-mvcc/dead-tuples-and-bloat.yaml", "llms": "docs/public/llms-full.txt#section=postgres/04-mvcc/dead-tuples-and-bloat.yaml", "metadata": "lead included scenario claim supplies built description/TechArticle where configured" } ] }, { "id": "P26", "path": "scenarios/postgres/04-mvcc/long-transactions.ts", "engine": "PostgreSQL", "observed_version": "18.6", "manual_version": "18", "evidence": { "scenarios": ["scenarios/postgres/04-mvcc/long-transactions.ts"], "official_manual_sections": [ "https://www.postgresql.org/docs/18/routine-vacuuming.html#VACUUM-FOR-SPACE-RECOVERY", "https://www.postgresql.org/docs/18/monitoring-stats.html#MONITORING-PG-STAT-ACTIVITY-VIEW", "https://www.postgresql.org/docs/18/runtime-config-client.html" ] }, "revisions": { "base": { "sha256": "a48bc2d5cc1134fe892455a62ea6213de290060b8d98153ec4adaa4e542f0f69", "schedule_occurrences": [ { "start": 17, "finish": 17, "session": "A", "sql": "BEGIN ISOLATION LEVEL REPEATABLE READ", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/long-transactions.ts#run.operation[0]" }, { "start": 18, "finish": 18, "session": "A", "sql": "SELECT xmin, id, status FROM jobs", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/long-transactions.ts#run.operation[1]" }, { "start": 21, "finish": 21, "session": "B", "sql": "UPDATE jobs SET status = 'running' WHERE id = 1 RETURNING xmin, status", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/long-transactions.ts#run.operation[2]" }, { "start": 22, "finish": 22, "session": "B", "sql": "UPDATE jobs SET status = 'done' WHERE id = 1 RETURNING xmin, status", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/long-transactions.ts#run.operation[3]" }, { "start": 23, "finish": 23, "session": "B", "sql": "UPDATE jobs SET status = 'archived' WHERE id = 1 RETURNING xmin, status", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/long-transactions.ts#run.operation[4]" }, { "start": 31, "finish": 33, "session": "B", "sql": "SELECT lp, t_xmin, t_xmax, t_ctid\n FROM heap_page_items(get_raw_page('jobs', 0)) ORDER BY lp", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/long-transactions.ts#run.operation[5]" }, { "start": 36, "finish": 36, "session": "B", "sql": "VACUUM jobs", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/long-transactions.ts#run.operation[6]" }, { "start": 40, "finish": 42, "session": "B", "sql": "SELECT lp, t_xmin, t_xmax, t_ctid\n FROM heap_page_items(get_raw_page('jobs', 0)) ORDER BY lp", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/long-transactions.ts#run.operation[7]" }, { "start": 46, "finish": 46, "session": "A", "sql": "SELECT id, status FROM jobs", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/long-transactions.ts#run.operation[8]" }, { "start": 48, "finish": 48, "session": "A", "sql": "COMMIT", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/long-transactions.ts#run.operation[9]" }, { "start": 50, "finish": 50, "session": "B", "sql": "VACUUM jobs", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/long-transactions.ts#run.operation[10]" }, { "start": 52, "finish": 54, "session": "B", "sql": "SELECT lp, lp_flags, t_xmin, t_xmax, t_ctid\n FROM heap_page_items(get_raw_page('jobs', 0)) ORDER BY lp", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/long-transactions.ts#run.operation[11]" } ] }, "current": { "sha256": "54918a48d201a4004ed1a83623b5ed8de5a17ae3670aa98a195cd4bb956ac21a", "schedule_occurrences": [ { "start": 17, "finish": 17, "session": "A", "sql": "BEGIN ISOLATION LEVEL REPEATABLE READ", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/long-transactions.ts#run.operation[0]" }, { "start": 18, "finish": 18, "session": "A", "sql": "SELECT xmin, id, status FROM jobs", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/long-transactions.ts#run.operation[1]" }, { "start": 21, "finish": 21, "session": "B", "sql": "UPDATE jobs SET status = 'running' WHERE id = 1 RETURNING xmin, status", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/long-transactions.ts#run.operation[2]" }, { "start": 22, "finish": 22, "session": "B", "sql": "UPDATE jobs SET status = 'done' WHERE id = 1 RETURNING xmin, status", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/long-transactions.ts#run.operation[3]" }, { "start": 23, "finish": 23, "session": "B", "sql": "UPDATE jobs SET status = 'archived' WHERE id = 1 RETURNING xmin, status", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/long-transactions.ts#run.operation[4]" }, { "start": 31, "finish": 33, "session": "B", "sql": "SELECT lp, t_xmin, t_xmax, t_ctid\n FROM heap_page_items(get_raw_page('jobs', 0)) ORDER BY lp", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/long-transactions.ts#run.operation[5]" }, { "start": 36, "finish": 36, "session": "B", "sql": "VACUUM jobs", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/long-transactions.ts#run.operation[6]" }, { "start": 40, "finish": 42, "session": "B", "sql": "SELECT lp, t_xmin, t_xmax, t_ctid\n FROM heap_page_items(get_raw_page('jobs', 0)) ORDER BY lp", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/long-transactions.ts#run.operation[7]" }, { "start": 46, "finish": 46, "session": "A", "sql": "SELECT id, status FROM jobs", "scope": "PostgreSQL 18.6; 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B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[1]" }, { "start": 18, "finish": 18, "session": "A", "sql": "SELECT pg_current_xact_id_if_assigned() AS xid", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[2]" }, { "start": 21, "finish": 21, "session": "A", "sql": "UPDATE accounts SET balance = 150 WHERE id = 1", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[3]" }, { "start": 22, "finish": 22, "session": "A", "sql": "SELECT pg_current_xact_id_if_assigned() AS xid", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[4]" }, { "start": 27, "finish": 27, "session": "B", "sql": "UPDATE accounts SET balance = 200 WHERE id = 2 RETURNING xmin, balance", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[5]" }, { "start": 31, "finish": 31, "session": "C", "sql": "BEGIN ISOLATION LEVEL REPEATABLE READ", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[6]" }, { "start": 32, "finish": 34, "session": "C", "sql": "SELECT pg_snapshot_xmin(pg_current_snapshot()) AS xmin,\n pg_snapshot_xmax(pg_current_snapshot()) AS xmax", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[7]" }, { "start": 41, "finish": 41, "session": "C", "sql": "SELECT pg_snapshot_xip(pg_current_snapshot()) AS xid", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[8]" }, { "start": 45, "finish": 45, "session": "C", "sql": "SELECT id, owner, balance FROM accounts ORDER BY id", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[9]" }, { "start": 51, "finish": 51, "session": "A", "sql": "COMMIT", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[10]" }, { "start": 53, "finish": 53, "session": "C", "sql": "SELECT id, owner, balance FROM accounts ORDER BY id", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[11]" }, { "start": 56, "finish": 56, "session": "C", "sql": "COMMIT", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[12]" }, { "start": 58, "finish": 58, "session": "C", "sql": "SELECT id, owner, balance FROM accounts ORDER BY id", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[13]" } ] }, "current": { "sha256": "0a2984a81816b00d2efd35e1895269c94128079fb634c209cff4fec913004576", "schedule_occurrences": [ { "start": 18, "finish": 18, "session": "A", "sql": "BEGIN", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[0]" }, { "start": 19, "finish": 19, "session": "A", "sql": "SELECT balance FROM accounts WHERE id = 1", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[1]" }, { "start": 20, "finish": 20, "session": "A", "sql": "SELECT pg_current_xact_id_if_assigned() AS xid", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[2]" }, { "start": 23, "finish": 23, "session": "A", "sql": "UPDATE accounts SET balance = 150 WHERE id = 1", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[3]" }, { "start": 24, "finish": 24, "session": "A", "sql": "SELECT pg_current_xact_id_if_assigned() AS xid", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[4]" }, { "start": 29, "finish": 29, "session": "B", "sql": "UPDATE accounts SET balance = 200 WHERE id = 2 RETURNING xmin, balance", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[5]" }, { "start": 33, "finish": 33, "session": "C", "sql": "BEGIN ISOLATION LEVEL REPEATABLE READ", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[6]" }, { "start": 34, "finish": 36, "session": "C", "sql": "SELECT pg_snapshot_xmin(pg_current_snapshot()) AS xmin,\n pg_snapshot_xmax(pg_current_snapshot()) AS xmax", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[7]" }, { "start": 43, "finish": 43, "session": "C", "sql": "SELECT pg_snapshot_xip(pg_current_snapshot()) AS xid", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[8]" }, { "start": 47, "finish": 47, "session": "C", "sql": "SELECT id, owner, balance FROM accounts ORDER BY id", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "explicit active", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[9]" }, { "start": 53, "finish": 53, "session": "A", "sql": "COMMIT", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"explicit active\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[10]" }, { "start": 55, "finish": 55, "session": "C", "sql": "SELECT id, owner, balance FROM accounts ORDER BY id", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "explicit active", "level": "REPEATABLE READ", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[11]" }, { "start": 58, "finish": 58, "session": "C", "sql": "COMMIT", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"explicit active\",\"level\":\"REPEATABLE READ\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[12]" }, { "start": 60, "finish": 60, "session": "C", "sql": "SELECT id, owner, balance FROM accounts ORDER BY id", "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; B={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}; C={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "B": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" }, "C": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } }, "occurrence": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts#run.operation[13]" } ] } }, "mirrors": [ { "scenario": "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts", "transcript": "docs/postgres/04-mvcc/parts/snapshots-under-the-hood.md", "ledger": "docs/public/ledger.jsonl#scenario=postgres/04-mvcc/snapshots-under-the-hood.ts", "llms": "docs/public/llms-full.txt#section=postgres/04-mvcc/snapshots-under-the-hood.ts", "metadata": "lead included scenario claim supplies built description/TechArticle where configured" } ] }, { "id": "P29", "path": "scenarios/postgres/04-mvcc/vacuum.yaml", "engine": "PostgreSQL", "observed_version": "18.6", "manual_version": "18", "evidence": { "scenarios": ["scenarios/postgres/04-mvcc/vacuum.yaml"], "official_manual_sections": [ "https://www.postgresql.org/docs/18/routine-vacuuming.html#VACUUM-FOR-SPACE-RECOVERY", "https://www.postgresql.org/docs/18/sql-vacuum.html", "https://www.postgresql.org/docs/18/pageinspect.html", "https://www.postgresql.org/docs/18/storage-hot.html", "https://www.postgresql.org/docs/18/runtime-config-vacuum.html#GUC-VACUUM-TRUNCATE", "https://www.postgresql.org/docs/18/explicit-locking.html#LOCKING-TABLES", "https://github.com/postgres/postgres/blob/REL_18_STABLE/src/include/storage/itemid.h" ] }, "revisions": { "base": { "sha256": "27c6e4feddef08cf527d0dfb23c1a75e6b4aec3e39267d3127649eee4992bb08", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[0]", "session": null, "sql": null, "fields": { "note": "Three updates leave three dead tuples on the page (the bloat lesson showed the chain)." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[1]", "session": "A", "sql": "UPDATE counters SET n = 1 WHERE id = 1", "fields": { "A": "UPDATE counters SET n = 1 WHERE id = 1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[2]", "session": "A", "sql": "UPDATE counters SET n = 2 WHERE id = 1", "fields": { "A": "UPDATE counters SET n = 2 WHERE id = 1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[3]", "session": "A", "sql": "UPDATE counters SET n = 3 WHERE id = 1 RETURNING xmin, n", "fields": { "A": "UPDATE counters SET n = 3 WHERE id = 1 RETURNING xmin, n", "capture": "last" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[4]", "session": "A", "sql": "VACUUM counters", "fields": { "A": "VACUUM counters" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[5]", "session": null, "sql": null, "fields": { "note": "After VACUUM: slot 1 is a redirect to the live version, slots 2–3 are unused (reusable), only slot 4 still holds a tuple. The corpses are gone." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[6]", "session": "A", "sql": "SELECT lp, lp_flags, t_xmin, t_xmax, t_ctid\nFROM heap_page_items(get_raw_page('counters', 0)) ORDER BY lp\n", "fields": { "A": "SELECT lp, lp_flags, t_xmin, t_xmax, t_ctid\nFROM heap_page_items(get_raw_page('counters', 0)) ORDER BY lp\n", "expect": [ { "lp": 1, "lp_flags": 2, "t_xmin": null, "t_xmax": null, "t_ctid": null }, { "lp": 2, "lp_flags": 0, "t_xmin": null, "t_xmax": null, "t_ctid": null }, { "lp": 3, "lp_flags": 0, "t_xmin": null, "t_xmax": null, "t_ctid": null }, { "lp": 4, "lp_flags": 1, "t_xmin": "${last.xmin}", "t_xmax": 0, "t_ctid": "(0,4)" } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[7]", "session": null, "sql": null, "fields": { "note": "The freed space is immediately reusable: the next INSERT lands in slot 2." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[8]", "session": "A", "sql": "INSERT INTO counters VALUES (2, 0) RETURNING ctid, id", "fields": { "A": "INSERT INTO counters VALUES (2, 0) RETURNING ctid, id", "expect": [ { "ctid": "(0,2)" } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[9]", "session": null, "sql": null, "fields": { "note": "Same story at file level — 1000 rows in 5 pages, doubled to 9 by an UPDATE of every row." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[10]", "session": "A", "sql": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "fields": { "A": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "expect": [ { "pages": 5 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[11]", "session": "A", "sql": "UPDATE bloat SET filler = 'y'", "fields": { "A": "UPDATE bloat SET filler = 'y'" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[12]", "session": "A", "sql": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "fields": { "A": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "expect": [ { "pages": 9 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[13]", "session": "A", "sql": "VACUUM bloat", "fields": { "A": "VACUUM bloat" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[14]", "session": null, "sql": null, "fields": { "note": "VACUUM cleaned 1000 dead tuples — and the file is still 9 pages. The space is free *inside* the file." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[15]", "session": "A", "sql": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "fields": { "A": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "expect": [ { "pages": 9 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[16]", "session": "A", "sql": "VACUUM FULL bloat", "fields": { "A": "VACUUM FULL bloat" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[17]", "session": null, "sql": null, "fields": { "note": "VACUUM FULL rewrites the table from scratch — back to 5 pages. The price: it holds ACCESS EXCLUSIVE for the whole rewrite." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[18]", "session": "A", "sql": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "fields": { "A": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "expect": [ { "pages": 5 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] }, "current": { "sha256": "922fc933ee71390ad3c03da2f1bf7dc35e12ddd0c1198782c646fb8b85b10ace", "schedule_occurrences": [ { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[0]", "session": null, "sql": null, "fields": { "note": "Three updates leave three dead tuples on the page (the bloat lesson showed the chain)." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[1]", "session": "A", "sql": "UPDATE counters SET n = 1 WHERE id = 1", "fields": { "A": "UPDATE counters SET n = 1 WHERE id = 1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[2]", "session": "A", "sql": "UPDATE counters SET n = 2 WHERE id = 1", "fields": { "A": "UPDATE counters SET n = 2 WHERE id = 1" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[3]", "session": "A", "sql": "UPDATE counters SET n = 3 WHERE id = 1 RETURNING xmin, n", "fields": { "A": "UPDATE counters SET n = 3 WHERE id = 1 RETURNING xmin, n", "capture": "last" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[4]", "session": "A", "sql": "VACUUM counters", "fields": { "A": "VACUUM counters" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[5]", "session": null, "sql": null, "fields": { "note": "After VACUUM: slot 1 is a redirect to the live version, slots 2–3 are unused (reusable), only slot 4 still holds a tuple. The corpses are gone." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[6]", "session": "A", "sql": "SELECT lp, lp_flags, t_xmin, t_xmax, t_ctid\nFROM heap_page_items(get_raw_page('counters', 0)) ORDER BY lp\n", "fields": { "A": "SELECT lp, lp_flags, t_xmin, t_xmax, t_ctid\nFROM heap_page_items(get_raw_page('counters', 0)) ORDER BY lp\n", "expect": [ { "lp": 1, "lp_flags": 2, "t_xmin": null, "t_xmax": null, "t_ctid": null }, { "lp": 2, "lp_flags": 0, "t_xmin": null, "t_xmax": null, "t_ctid": null }, { "lp": 3, "lp_flags": 0, "t_xmin": null, "t_xmax": null, "t_ctid": null }, { "lp": 4, "lp_flags": 1, "t_xmin": "${last.xmin}", "t_xmax": 0, "t_ctid": "(0,4)" } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[7]", "session": null, "sql": null, "fields": { "note": "The freed space is immediately reusable: the next INSERT lands in slot 2." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[8]", "session": "A", "sql": "INSERT INTO counters VALUES (2, 0) RETURNING ctid, id", "fields": { "A": "INSERT INTO counters VALUES (2, 0) RETURNING ctid, id", "expect": [ { "ctid": "(0,2)" } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[9]", "session": null, "sql": null, "fields": { "note": "At file level this 1000-row heap grows from 5 to 9 pages after UPDATE." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[10]", "session": "A", "sql": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "fields": { "A": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "expect": [ { "pages": 5 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[11]", "session": "A", "sql": "UPDATE bloat SET filler = 'y'", "fields": { "A": "UPDATE bloat SET filler = 'y'" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[12]", "session": "A", "sql": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "fields": { "A": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "expect": [ { "pages": 9 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[13]", "session": "A", "sql": "VACUUM bloat", "fields": { "A": "VACUUM bloat" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[14]", "session": null, "sql": null, "fields": { "note": "Standard VACUUM completes and the asserted file size remains 9 pages. This size observation does not count reclaimed tuples or reusable bytes." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[15]", "session": "A", "sql": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "fields": { "A": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "expect": [ { "pages": 9 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[16]", "session": "A", "sql": "VACUUM FULL bloat", "fields": { "A": "VACUUM FULL bloat" }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[17]", "session": null, "sql": null, "fields": { "note": "VACUUM FULL rewrites the table from scratch — back to 5 pages. The price: it holds ACCESS EXCLUSIVE for the whole rewrite." }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } }, { "occurrence": "scenarios/postgres/04-mvcc/vacuum.yaml#steps[18]", "session": "A", "sql": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "fields": { "A": "SELECT (pg_relation_size('bloat') / 8192)::int AS pages", "expect": [ { "pages": 5 } ] }, "scope": "PostgreSQL 18.6; ordered schedule state before operation: A={\"phase\":\"standalone\",\"level\":\"READ COMMITTED\",\"lock_timeout\":\"0\",\"deadlock_timeout\":\"1s\"}", "state_after": { "A": { "phase": "standalone", "level": "READ COMMITTED", "lock_timeout": "0", "deadlock_timeout": "1s" } } } ] } }, "mirrors": [ { "scenario": "scenarios/postgres/04-mvcc/vacuum.yaml", "transcript": "docs/postgres/04-mvcc/parts/vacuum.md", "ledger": "docs/public/ledger.jsonl#scenario=postgres/04-mvcc/vacuum.yaml", "llms": "docs/public/llms-full.txt#section=postgres/04-mvcc/vacuum.yaml", "metadata": "lead included scenario claim supplies built description/TechArticle where configured" } ] }, { "id": "P30", "path": "docs/.vitepress/config.ts", "scope": "Editorial chapter navigation/coverage labels; no additional universal database claim", "evidence": { "scenarios": [ "scenarios/postgres/03-locking/alter-table-outage.yaml", "scenarios/postgres/03-locking/ddl-lock-timeout.yaml", "scenarios/postgres/03-locking/deadlock-avoidance.yaml", "scenarios/postgres/03-locking/deadlock.yaml", "scenarios/postgres/03-locking/fk-key-share.yaml", "scenarios/postgres/03-locking/for-update-blocks.yaml", "scenarios/postgres/03-locking/lock-mode-matrix.yaml", "scenarios/postgres/03-locking/lock-queue-fifo.yaml", "scenarios/postgres/03-locking/lock-timeout.yaml", "scenarios/postgres/03-locking/monitoring-locks.yaml", "scenarios/postgres/03-locking/nowait.yaml", "scenarios/postgres/03-locking/skip-locked.yaml", "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml", "scenarios/postgres/04-mvcc/long-transactions.ts", "scenarios/postgres/04-mvcc/row-versions.ts", "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts", "scenarios/postgres/04-mvcc/vacuum.yaml" ] }, "revisions": {} }, { "id": "P31", "path": "README.md", "scope": "Editorial chapter navigation/coverage labels; no additional universal database claim", "evidence": { "scenarios": [ "scenarios/postgres/03-locking/alter-table-outage.yaml", "scenarios/postgres/03-locking/ddl-lock-timeout.yaml", "scenarios/postgres/03-locking/deadlock-avoidance.yaml", "scenarios/postgres/03-locking/deadlock.yaml", "scenarios/postgres/03-locking/fk-key-share.yaml", "scenarios/postgres/03-locking/for-update-blocks.yaml", "scenarios/postgres/03-locking/lock-mode-matrix.yaml", "scenarios/postgres/03-locking/lock-queue-fifo.yaml", "scenarios/postgres/03-locking/lock-timeout.yaml", "scenarios/postgres/03-locking/monitoring-locks.yaml", "scenarios/postgres/03-locking/nowait.yaml", "scenarios/postgres/03-locking/skip-locked.yaml", "scenarios/postgres/04-mvcc/dead-tuples-and-bloat.yaml", "scenarios/postgres/04-mvcc/long-transactions.ts", "scenarios/postgres/04-mvcc/row-versions.ts", "scenarios/postgres/04-mvcc/snapshots-under-the-hood.ts", "scenarios/postgres/04-mvcc/vacuum.yaml" ] }, "revisions": {} } ]