Cookbook recipe

synchronous_commit: durability vs latency

Applies to PostgreSQL 13–17 Last reviewed May 2026 Grounded in source

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Estimated investigation4 min

Scenario

Commits feel slow under synchronous replication, or you fear data loss with async. Choose the right durability level per workload. Diagnose it Check current durability mode: SHOW synchronous_commit; SHOW synchronous_standby_names; Why it happens synchronous_commit controls when…

Investigation Path

Commits feel slow under synchronous replication, or you fear data loss with async. Choose the right durability level per workload.

Diagnose it

Check current durability mode:

SHOW synchronous_commit;
SHOW synchronous_standby_names;

Why it happens

synchronous_commit controls when COMMIT returns: on waits for local WAL flush; remote_apply/remote_write/on with sync standbys wait for the replica; off returns before flush (fast, small risk of losing the last transactions on crash).

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Related & next steps

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Concepts on this page

Replication
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