PostgreSQL stale replication slot

Description

Stale replication slots will lead to WAL file accumulation. This can result in a DB server outage.

A stale replication slot is a slot that satisfies the following criteria: - Not a temporary slot. - Not an active slot. - WAL distance between current WAL position and slot’s restart LSN is more than the current setting for the max_wal_size configuration option.

Resolution

Review the output of SELECT * FROM pg_replication_slots and identify the slots that are inactive and have an old restart_lsn.

Drop such slots as soon as possible. You can recreate the slot, but note that the receiving end might need to be resynchronized.

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