The following documentation comment has been logged on the website: Page: https://www.postgresql.org/docs/16/routine-vacuuming.html Description:
In https://www.postgresql.org/docs/current/routine-vacuuming.html section "25.1.5. Preventing Transaction ID Wraparound Failures" there is a 5-step procedure to handle the "database is not accepting commands" situation, see "Instead, follow these steps:" Please, add a notice about temporary tables - they can also prevent vacuuming! This is hinted in section "25.1.6. The Autovacuum Daemon", but only indirectly: "Temporary tables cannot be accessed by autovacuum. Therefore, appropriate vacuum and analyze operations should be performed via session SQL commands." Just today on a production, I performed (in a single-user mode) vacuum, even vacuum freeze, and after ending it, DB still didn't accept users. The useful detection SELECT was SELECT oid, oid::regclass, relkind, relfrozenxid, age(relfrozenxid) FROM pg_class WHERE relfrozenxid <> 0 ORDER BY age(relfrozenxid); Then I realized these were the temporary tables and dropped all the temporary schemas ... once in a single-user mode :(
