4Failure response

• 4.1Common failure patterns

  Learn the basics of failure triage: identifying issues from error messages, server stoppage, data loss, OS resource exhaustion, and process-state analysis; the timeout parameters statement_timeout, lock_timeout, and idle_in_transaction_session_timeout; synchronous_commit and restart_after_crash which govern post-crash consistency; server control via pg_ctl; and the lock-management ceiling max_locks_per_transaction.

• 4.2Recovering a corrupted cluster

  Learn the procedures for recovering a corrupted database cluster: PITR (point-in-time recovery) as the central technique, pg_resetwal which rebuilds WAL control information, the startup troubleshooting flags ignore_system_indexes and ignore_checksum_failure, pg_xact which holds the commit log, emergency single-user mode, and VACUUM FREEZE as the countermeasure for transaction ID wraparound.

• 4.3Replication failures and recovery

  Learn how to handle failures while running replication: pg_ctl promote, which promotes a standby to primary; pg_rewind, which re-synchronizes an old primary as a standby of the new one; pg_receivewal, which continuously receives WAL directly; the conflicts unique to logical replication; and error handling for streaming replication.