Postgres FM

Nik and Michael discuss when not to use Postgres — specifically use cases where it still makes sense to store data in another system. Here are some links to things they mentioned:Just use Postgres (blog post by Ethan McCue) https://mccue.dev/pages/8-16-24-just-use-postgresJust Use Postgres for Everything (blog post by Stephan Schmidt) https://www.amazingcto.com/postgres-for-everythingReal-time analytics episode https://postgres.fm/episodes/real-time-analyticsCrunchy Data Joins Snowflake https://www.crunchydata.com/blog/crunchy-data-joins-snowflakeTwo sizes fit most: PostgreSQL and Clickhouse (blog post by Sid Sijbrandij) https://about.gitlab.com/blog/two-sizes-fit-most-postgresql-and-clickhousepg_duckdb episode https://postgres.fm/episodes/pg_duckdbCloudberry https://github.com/apache/cloudberryTime-series considerations episode https://postgres.fm/episodes/time-series-considerationsQueues in Postgres episode https://postgres.fm/episodes/queues-in-postgresLarge Objects https://www.postgresql.org/docs/current/largeobjects.html PGlite https://pglite.devParadeDB https://www.paradedb.comZomboDB https://github.com/zombodb/zombodbturbopuffer https://turbopuffer.comHNSW vs. DiskANN (blog post by Haziqa Sajid) https://www.tigerdata.com/learn/hnsw-vs-diskannSPANN: Highly-efficient Billion-scale Approximate Nearest Neighbor Search (paper) https://www.microsoft.com/en-us/research/wp-content/uploads/2021/11/SPANN_finalversion1.pdfAmazon S3 Vectors https://aws.amazon.com/s3/features/vectorsIterative Index Scans added to pgvector in 0.8.0 https://github.com/pgvector/pgvector/issues/678S3 FDW from Supabase https://github.com/supabase/wrappers/tree/main/wrappers/src/fdw/s3_fdw~~~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 pgMustardNikolay Samokhvalov, founder of Postgres.aiWith credit to:Jessie Draws for the elephant artwork

Nik and Michael discuss disks in relation to Postgres — why they matter, how saturation can happen, some modern nuances, and how to prepare to avoid issues. Here are some links to things they mentioned:Nik’s tweet demonstrating a NOTIFY hot spot https://x.com/samokhvalov/status/1959468091035009245Postgres LISTEN/NOTIFY does not scale (blog post by Recall ai) https://www.recall.ai/blog/postgres-listen-notify-does-not-scaletrack_io_timing https://www.postgresql.org/docs/current/runtime-config-statistics.html#GUC-TRACK-IO-TIMINGpg_test_timing https://www.postgresql.org/docs/current/pgtesttiming.html PlanetScale for Postgres https://planetscale.com/blog/planetscale-for-postgresOut of disk episode https://postgres.fm/episodes/out-of-disk100TB episode https://postgres.fm/episodes/to-100tb-and-beyond Latency Numbers Every Programmer Should Know https://gist.github.com/jboner/2841832Fio https://github.com/axboe/fio~~~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 pgMustardNikolay Samokhvalov, founder of Postgres.aiWith credit to:Jessie Draws for the elephant artwork

Nik and Michael discuss multi-column indexes in Postgres — what they are, how to think about them, and some guidance around using them effectively. Here are some links to things they mentioned:Multicolumn Indexes (docs) https://www.postgresql.org/docs/current/indexes-multicolumn.htmlOur episode on Index-only scans https://postgres.fm/episodes/index-only-scansCombining Multiple Indexes (docs) https://www.postgresql.org/docs/current/indexes-bitmap-scans.htmlEnable BUFFERS with EXPLAIN ANALYZE by default https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=c2a4078ebad71999dd451ae7d4358be3c9290b07“PostgreSQL includes an implementation of the standard btree […] The only limitation is that an index entry cannot exceed approximately one-third of a page” https://www.postgresql.org/docs/current/btree.htmlOur episode on HOT updates https://postgres.fm/episodes/hot-updatesOur episode on LIMIT vs Performance https://postgres.fm/episodes/limit-vs-performance~~~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 pgMustardNikolay Samokhvalov, founder of Postgres.aiWith credit to:Jessie Draws for the elephant artwork

Nikolay and Michael discuss self-driving Postgres — what it could mean, using self-driving cars as a reference, and ideas for things to build and optimize for in this area. Here are some links to things they mentioned:Nikolay’s blog post on Self-driving Postgres https://postgres.ai/blog/20250725-self-driving-postgresSAE J3016 levels of driving automation https://www.sae.org/news/2019/01/sae-updates-j3016-automated-driving-graphicOracle Autonomous Database https://www.oracle.com/uk/autonomous-database/Self-Driving Database Management Systems (2017 paper) https://db.cs.cmu.edu/papers/2017/p42-pavlo-cidr17.pdfPGTune https://pgtune.leopard.in.ua/pg_index_pilot https://gitlab.com/postgres-ai/pg_index_pilot/[Vibe] Hacking Postgres with Andrey, Kirk, Nik – index bloat, btree page merge https://www.youtube.com/watch?v=D1PEdDcvZTw~~~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 pgMustardNikolay Samokhvalov, founder of Postgres.aiWith credit to:Jessie Draws for the elephant artwork

Nikolay and Michael discuss case-insensitive data — when we want to treat columns as case-insensitive, and the pros and cons of using citext, functions like lower(), or a custom collation. Here are some links to things they mentioned:citext https://www.postgresql.org/docs/current/citext.htmlOur episode on over-indexing https://postgres.fm/episodes/over-indexingNondeterministic collations https://www.postgresql.org/docs/current/collation.html#COLLATION-NONDETERMINISTICHow to migrate from Django’s PostgreSQL CI Fields to use a case-insensitive collation (blog post by Adam Johnson) https://adamj.eu/tech/2023/02/23/migrate-django-postgresql-ci-fields-case-insensitive-collationThe collation versioning problem with ICU 73 (blog post by Daniel Vérité) https://postgresql.verite.pro/blog/2023/10/20/icu-73-versioning.htmlamcheck https://www.postgresql.org/docs/current/amcheck.html~~~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 pgMustardNikolay Samokhvalov, founder of Postgres.aiWith credit to:Jessie Draws for the elephant artwork

Nikolay talks to Michael about Postgres AI's new monitoring tool — what it is, how its different to other tools, and some of the thinking behind it. Here are some links to things they mentioned:postgres_ai monitoring https://gitlab.com/postgres-ai/postgres_aiDB Lab 4.0 announcement https://github.com/postgres-ai/database-lab-engine/releases/tag/v4.0.0pganalyze https://pganalyze.compostgres-checkup https://gitlab.com/postgres-ai/postgres-checkupPercona Monitoring and Management (PMM) https://github.com/percona/pmmpgwatch https://github.com/cybertec-postgresql/pgwatchpgwatch Postgres AI Edition https://gitlab.com/postgres-ai/pgwatch2libpg_query https://github.com/pganalyze/libpg_queryThe Four Golden Signals https://sre.google/sre-book/monitoring-distributed-systems/#xref_monitoring_golden-signalslogerrors https://github.com/munakoiso/logerrors~~~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 pgMustardNikolay Samokhvalov, founder of Postgres.aiWith credit to:Jessie Draws for the elephant artwork

Nikolay and Michael are joined by Andrew Johnson and Nate Brennand from Metronome to discuss MultiXact member space exhaustion — what it is, how they managed to hit it, and some tips to prevent running into it at scale. Here are some links to things they mentioned:Nate Brennand https://postgres.fm/people/nate-brennandAndrew Johnson https://postgres.fm/people/andrew-johnsonMetronome https://metronome.comRoot Cause Analysis: PostgreSQL MultiXact member exhaustion incidents (blog post by Metronome) https://metronome.com/blog/root-cause-analysis-postgresql-multixact-member-exhaustion-incidents-may-2025Multixacts and Wraparound (docs) https://www.postgresql.org/docs/current/routine-vacuuming.html#VACUUM-FOR-MULTIXACT-WRAPAROUNDmultixact.c source code https://github.com/postgres/postgres/blob/master/src/backend/access/transam/multixact.cAdd pg_stat_multixact view for multixact membership usage monitoring (patch proposal by Andrew, needing review!) https://commitfest.postgresql.org/patch/5869/PostgreSQL subtransactions considered harmful (blog post by Nikolay) https://postgres.ai/blog/20210831-postgresql-subtransactions-considered-harmfulvacuum_multixact_failsafe_age doesn't account for MultiXact member exhaustion (thread started by Peter Geoghegan) https://www.postgresql.org/message-id/flat/CAH2-WzmLPWJk3gbAxy8dHY%2BA-Juz_6uGwfe6DkE8B5-dTDvLcw%40mail.gmail.comAmazon S3 Vectors https://aws.amazon.com/blogs/aws/introducing-amazon-s3-vectors-first-cloud-storage-with-native-vector-support-at-scale/MultiXacts in PostgreSQL: usage, side effects, and monitoring (blog post by Shawn McCoy and Divya Sharma from AWS) https://aws.amazon.com/blogs/database/multixacts-in-postgresql-usage-side-effects-and-monitoring/Postgres Aurora multixact monitoring queries https://gist.github.com/natebrennand/0924f723ff61fa897c4106379fc7f3dc And finally an apology and a correction, the membership space is ~4B, not ~2B as said by Michael in the episode! Definition here:https://github.com/postgres/postgres/blob/f6ffbeda00e08c4c8ac8cf72173f84157491bfde/src/include/access/multixact.h#L31And here's the formula discussed for calculating how the member space can grow quadratically by the number of overlapping transactions:Members can be calculated via: aₙ = 2 + [sum from k=3 to n+1 of k]This simplifies to: aₙ = (((n+1)(n+2))/2) - 1~~~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 pgMustardNikolay Samokhvalov, founder of Postgres.aiWith special thanks to:Jessie Draws for the elephant artwork 

Nikolay and Michael are joined by Sugu Sougoumarane to discuss Multigres — a project he's joined Supabase to lead, building an adaptation of Vitess for Postgres! Here are some links to things they mentioned:Sugu Sougoumarane https://postgres.fm/people/sugu-sougoumaraneSupabase https://supabase.comAnnouncing Multigres https://supabase.com/blog/multigres-vitess-for-postgresVitess https://github.com/vitessio/vitessSPQR https://github.com/pg-sharding/spqrCitus https://github.com/citusdata/citusPgDog https://github.com/pgdogdev/pgdogMyths and Truths about Synchronous Replication in PostgreSQL (talk by Alexander Kukushkin) https://www.youtube.com/watch?v=PFn9qRGzTMcConsensus algorithms at scale (8 part series by Sugu) https://planetscale.com/blog/consensus-algorithms-at-scale-part-1A More Flexible Paxos (blog post by Sugu) https://www.sougou.io/a-more-flexible-paxoslibpg_query https://github.com/pganalyze/libpg_queryPL/Proxy https://github.com/plproxy/plproxyPlanetScale Postgres Benchmarking https://planetscale.com/blog/benchmarking-postgresMultiXact member exhaustion incidents (blog post by Cosmo Wolfe / Metronome) https://metronome.com/blog/root-cause-analysis-postgresql-multixact-member-exhaustion-incidents-may-2025~~~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 pgMustardNikolay Samokhvalov, founder of Postgres.aiWith special thanks to:Jessie Draws for the elephant artwork 

Nikolay and Michael are joined by Gwen Shapira to discuss multi-tenant architectures — the high level options, the pros and cons of each, and how they're trying to help with Nile. Here are some links to things they mentioned:Gwen Shapira https://postgres.fm/people/gwen-shapiraNile https://www.thenile.devSaaS Tenant Isolation Strategies (AWS whitepaper) https://docs.aws.amazon.com/whitepapers/latest/saas-tenant-isolation-strategies/saas-tenant-isolation-strategies.html Row Level Security https://www.postgresql.org/docs/current/ddl-rowsecurity.htmlCitus https://github.com/citusdata/citusPostgres.AI Bot https://postgres.ai/blog/20240127-postgres-ai-bot RLS Performance and Best Practices https://supabase.com/docs/guides/troubleshooting/rls-performance-and-best-practices-Z5JjwvCase Gwen mentioned about the planner thinking an optimisation was unsafe Re-engineering Postgres for Millions of Tenants (Gwen’s recent talk at PGConf.dev) https://www.youtube.com/watch?v=EfAStGb4s88 Multi-tenant database the good, the bad, the ugly (talk by Pierre Ducroquet at PgDay Paris) https://www.youtube.com/watch?v=4uxuPfSvTGU ~~~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 pgMustardNikolay Samokhvalov, founder of Postgres.aiWith special thanks to:Jessie Draws for the elephant artwork 

Nikolay and Michael discuss looking at queries by mean time — when it makes sense, why ordering by a percentile (like p99) might be better, and the merits of approximating percentiles in pg_stat_statements using the standard deviation column. Here are some links to things they mentioned:Approximate the p99 of a query with pg_stat_statements (blog post by Michael) https://www.pgmustard.com/blog/approximate-the-p99-of-a-query-with-pgstatstatementspg_stat_statements https://www.postgresql.org/docs/current/pgstatstatements.html Our episode about track_planning https://postgres.fm/episodes/pg-stat-statements-track-planning pg_stat_monitor https://github.com/percona/pg_stat_monitorstatement_timeout https://www.postgresql.org/docs/current/runtime-config-client.html#GUC-STATEMENT-TIMEOUT~~~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 pgMustardNikolay Samokhvalov, founder of Postgres.aiWith credit to:Jessie Draws for the elephant artwork