synchronous_commit

Postgres FM

Nikolay and Michael discuss synchronous_commit — what it means on single node setups, for synchronous replication setups, and the pros and cons of the different options for each.
Here are some links to things they mentioned:

• synchronous_commit https://www.postgresql.org/docs/current/runtime-config-wal.html#GUC-SYNCHRONOUS-COMMIT
• synchronous_commit history on pgPedia https://pgpedia.info/s/synchronous_commit.html
• Patroni’s maximum_lag_on_failover setting https://patroni.readthedocs.io/en/master/replication_modes.html#asynchronous-mode-durability
• wal_writer_delay https://www.postgresql.org/docs/current/runtime-config-wal.html#GUC-WAL-WRITER-DELAY
• Selective asynchronous commits in PostgreSQL - balancing durability and performance (blog post by Shayon Mukherjee) https://www.shayon.dev/post/2025/75/selective-asynchronous-commits-in-postgresql-balancing-durability-and-performance/
• Asynchronous Commit https://www.postgresql.org/docs/current/wal-async-commit.html
• synchronous_standby_names https://www.postgresql.org/docs/current/runtime-config-replication.html#GUC-SYNCHRONOUS-STANDBY-NAMES
• Jepson article about Amazon RDS multi-AZ clusters (by Kyle Kingsbury, aka "Aphyr”) https://jepsen.io/analyses/amazon-rds-for-postgresql-17.4

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What did you like or not like? What should we discuss next time? Let us know via a YouTube comment, on social media, or by commenting on our Google doc!

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Postgres FM is produced by:

• Michael Christofides, founder of pgMustard
• Nikolay Samokhvalov, founder of Postgres.ai

With credit to:

• Jessie Draws for the elephant artwork