Plan flips

Nik and Michael discuss query plan flips in Postgres — what they are, some causes, mitigations, longer term solutions, and the recent outage at Clerk.

Here are some links to things they mentioned:
• Recent postmortem from Clerk clerk.com/blog/2026-02-19-system-outage-postmo…
• The real cost of random I/O (blog post by Tomas Vondra) vondra.me/posts/the-real-cost-of-random-io
• autovacuum_analyze_scale_factor postgresql.org/docs/current/runtime-config-vac…
• default_statistics_target postgresql.org/docs/current/runtime-config-que…
• pg_hint_plan github.com/ossc-db/pg_hint_plan
• Aurora PostgreSQL query plan management docs.aws.amazon.comAmazonRDS/latest/AuroraUser… (docs.aws.amazon.com/AmazonRDS/latest/AuroraUse…)
• pg_stat_plans github.com/pganalyze/pg_stat_plans
• pg_plan_alternatives jnidzwetzki.github.io/2026/03/04/pg-plan-alter…
• Waiting for Postgres 19: Better Planner Hints with Path Generation Strategies pganalyze.com/blog/5mins-postgres-19-better-pl…

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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, (postgres.fm/people) or by commenting on our Google doc (docs.google.com/document/d/1PNGSn_d0A7gTR4C0p6…)!

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Postgres FM is produced by:
• Michael Christofides, founder of pgMustard (pgmustard.com)
• Nikolay Samokhvalov, founder of Postgres.ai (postgres.ai)

With credit to:
• Jessie Draws for the elephant artwork