LWLocks — Postgres FM

Nik and Michael discuss lightweight locks in Postgres — how they differ to (heavier) locks, some occasions they can be troublesome, and some resources for working out what to do if you hit issues.

Here are some links to things they mentioned:

Wait Events of Type LWLock https://www.postgresql.org/docs/current/monitoring-stats.html#WAIT-EVENT-LWLOCK-TABLE
Our episode on (heavier) locks https://postgres.fm/episodes/locks
Nik’s new marathon posts https://postgres.ai/blog/tags/postgres-marathon
Postgres LISTEN/NOTIFY does not scale (blog post by Recall ai) https://www.recall.ai/blog/postgres-listen-notify-does-not-scale
Explicit Locking https://www.postgresql.org/docs/current/explicit-locking.html
pg_stat_activity https://www.postgresql.org/docs/current/monitoring-stats.html#MONITORING-PG-STAT-ACTIVITY-VIEW
Tuning with wait events for RDS for PostgreSQL https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/PostgreSQL.Tuning.html
MultiXact member exhaustion incidents (blog post by Cosmo Wolfe / Metronome) https://metronome.com/blog/root-cause-analysis-postgresql-multixact-member-exhaustion-incidents-may-2025
pg_index_pilot https://gitlab.com/postgres-ai/pg_index_pilot
Myths and Truths about Synchronous Replication in PostgreSQL (talk by Alexander Kukushkin) https://www.youtube.com/watch?v=PFn9qRGzTMc
Postgres Indexes, Partitioning and LWLock:LockManager Scalability (blog post by Jeremy Schneider) https://ardentperf.com /2024/03/03/postgres-indexes-partitioning-and-lwlocklockmanager-scalability

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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