Postgres FM

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 https://clerk.com/blog/2026-02-19-system-outage-postmortem
The real cost of random I/O (blog post by Tomas Vondra) https://vondra.me/posts/the-real-cost-of-random-io
autovacuum_analyze_scale_factor https://www.postgresql.org/docs/current/runtime-config-vacuum.html#GUC-AUTOVACUUM-ANALYZE-SCALE-FACTOR
default_statistics_target https://www.postgresql.org/docs/current/runtime-config-query.html#GUC-DEFAULT-STATISTICS-TARGET
pg_hint_plan https://github.com/ossc-db/pg_hint_plan
Aurora PostgreSQL query plan management https://docs.aws.amazon.comAmazonRDS/latest/AuroraUserGuide/AuroraPostgreSQL.Optimize.Start.html
pg_stat_plans https://github.com/pganalyze/pg_stat_plans
pg_plan_alternatives https://jnidzwetzki.github.io/2026/03/04/pg-plan-alternatives.html
Waiting for Postgres 19: Better Planner Hints with Path Generation Strategies https://pganalyze.com/blog/5mins-postgres-19-better-planner-hints

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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

Nik and Michael discuss pg_ash — a new tool (not extension!) from Nik that samples and stores wait events from pg_stat_activity.
 
Here are some links to things they mentioned: 
pg_ash https://github.com/NikolayS/pg_ash
pg_wait_sampling https://github.com/postgrespro/pg_wait_sampling
Amazon RDS performance insights https://aws.amazon.com/rds/performance-insights
Our episode on wait events https://postgres.fm/episodes/wait-events
pg-flight-recorder https://github.com/dventimisupabase/pg-flight-recorder
pg_profile https://github.com/zubkov-andrei/pg_profile
pg_cron https://github.com/citusdata/pg_cron

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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

Nik and Michael discuss query level comments, object level comments, and another way of adding object level metadata.
 
Here are some links to things they mentioned: 
Object comments https://www.postgresql.org/docs/current/sql-comment.html
Query comment syntax (from an old version of the docs) https://www.postgresql.org/docs/7.0/syntax519.htm
SQL Comments, Please! (Post by Markus Winand) https://modern-sql.com/caniuse/comments
“While C-style block comments are passed to the server for processing and removal, SQL-standard comments are removed by psql.” https://www.postgresql.org/docs/current/app-psql.html
marginalia https://github.com/basecamp/marginalia
track_activity_query_size https://www.postgresql.org/docs/current/runtime-config-statistics.html#GUC-TRACK-ACTIVITY-QUERY-SIZE
Custom Properties for Database Objects Using SECURITY LABELS (post by Andrei Lepikhov) https://www.pgedge.com/blog/custom-properties-for-postgresql-database-objects-without-core-patches

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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!

~~~
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

Nik and Michael are joined by Lev Kokotov for an update on all things PgDog.
 
Here are some links to things they mentioned:
Lev Kokotov https://postgres.fm/people/lev-kokotov
PgDog https://github.com/pgdogdev/pgdog
Our first PgDog episode (March 2025) https://postgres.fm/episodes/pgdog
Sharding pgvector (blog post by Lev) https://pgdog.dev/blog/sharding-pgvector
Prepared statements and partitioned table lock explosion (series by Nik) https://postgres.ai/blog/20251028-postgres-marathon-2-009

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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!

~~~
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

Nik and Michael are joined by Radim Marek from boringSQL to talk about RegreSQL, a regression testing tool for SQL queries they forked and improved recently.
 
Here are some links to things they mentioned:
Radim Marek https://postgres.fm/people/radim-marek
boringSQL https://boringsql.com
RegreSQL: Regression Testing for PostgreSQL Queries (blog post by Radim) https://boringsql.com/posts/regresql-testing-queries
Discussion on Hacker News https://news.ycombinator.com/item?id=45924619 
Radim’s fork of RegreSQL on GitHub https://github.com/boringSQL/regresql 
Original RegreSQL on GitHub (by Dimitri Fontaine) https://github.com/dimitri/regresql 
The Art of PostgreSQL (book) https://theartofpostgresql.com
How to make the non-production Postgres planner behave like in production (how-to post by Nik) https://postgres.ai/docs/postgres-howtos/performance-optimization/query-tuning/how-to-imitate-production-planner 
Just because you’re getting an index scan, doesn't mean you can’t do better! (Blog post by Michael) https://www.pgmustard.com/blog/index-scan-doesnt-mean-its-fast
boringSQL Labs https://labs.boringsql.com

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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!

~~~
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