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-postgres
• Just Use Postgres for Everything (blog post by Stephan Schmidt) https://www.amazingcto.com/postgres-for-everything
• Real-time analytics episode https://postgres.fm/episodes/real-time-analytics
• Crunchy Data Joins Snowflake https://www.crunchydata.com/blog/crunchy-data-joins-snowflake
• Two sizes fit most: PostgreSQL and Clickhouse (blog post by Sid Sijbrandij) https://about.gitlab.com/blog/two-sizes-fit-most-postgresql-and-clickhouse
• pg_duckdb episode https://postgres.fm/episodes/pg_duckdb
• Cloudberry https://github.com/apache/cloudberry
• Time-series considerations episode https://postgres.fm/episodes/time-series-considerations
• Queues in Postgres episode https://postgres.fm/episodes/queues-in-postgres
• Large Objects https://www.postgresql.org/docs/current/largeobjects.html
• PGlite https://pglite.dev
• ParadeDB https://www.paradedb.com
• ZomboDB https://github.com/zombodb/zombodb
• turbopuffer https://turbopuffer.com
• HNSW vs. DiskANN (blog post by Haziqa Sajid) https://www.tigerdata.com/learn/hnsw-vs-diskann
• SPANN: Highly-efficient Billion-scale Approximate Nearest Neighbor Search (paper) https://www.microsoft.com/en-us/research/wp-content/uploads/2021/11/SPANN_finalversion1.pdf
• Amazon S3 Vectors https://aws.amazon.com/s3/features/vectors
• Iterative Index Scans added to pgvector in 0.8.0 https://github.com/pgvector/pgvector/issues/678
• S3 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 pgMustard
• Nikolay Samokhvalov, founder of Postgres.ai

With 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/1959468091035009245
• Postgres LISTEN/NOTIFY does not scale (blog post by Recall ai) https://www.recall.ai/blog/postgres-listen-notify-does-not-scale
• track_io_timing https://www.postgresql.org/docs/current/runtime-config-statistics.html#GUC-TRACK-IO-TIMING
• pg_test_timing https://www.postgresql.org/docs/current/pgtesttiming.html
• PlanetScale for Postgres https://planetscale.com/blog/planetscale-for-postgres
• Out of disk episode https://postgres.fm/episodes/out-of-disk
• 100TB episode https://postgres.fm/episodes/to-100tb-and-beyond
• Latency Numbers Every Programmer Should Know https://gist.github.com/jboner/2841832
• Fio 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 pgMustard
• Nikolay Samokhvalov, founder of Postgres.ai

With 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.html
• Our episode on Index-only scans https://postgres.fm/episodes/index-only-scans
• Combining Multiple Indexes (docs) https://www.postgresql.org/docs/current/indexes-bitmap-scans.html
• Enable 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.html
• Our episode on HOT updates https://postgres.fm/episodes/hot-updates
• Our 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 pgMustard
• Nikolay Samokhvalov, founder of Postgres.ai

With 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-postgres
• SAE J3016 levels of driving automation https://www.sae.org/news/2019/01/sae-updates-j3016-automated-driving-graphic
• Oracle 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.pdf
• PGTune 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 pgMustard
• Nikolay Samokhvalov, founder of Postgres.ai

With 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.html
• Our episode on over-indexing https://postgres.fm/episodes/over-indexing
• Nondeterministic collations https://www.postgresql.org/docs/current/collation.html#COLLATION-NONDETERMINISTIC
• How 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-collation
• The collation versioning problem with ICU 73 (blog post by Daniel Vérité) https://postgresql.verite.pro/blog/2023/10/20/icu-73-versioning.html
• amcheck 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 pgMustard
• Nikolay Samokhvalov, founder of Postgres.ai

With 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_ai
• DB Lab 4.0 announcement https://github.com/postgres-ai/database-lab-engine/releases/tag/v4.0.0
• pganalyze https://pganalyze.com
• postgres-checkup https://gitlab.com/postgres-ai/postgres-checkup
• Percona Monitoring and Management (PMM) https://github.com/percona/pmm
• pgwatch https://github.com/cybertec-postgresql/pgwatch
• pgwatch Postgres AI Edition https://gitlab.com/postgres-ai/pgwatch2
• libpg_query https://github.com/pganalyze/libpg_query
• The Four Golden Signals https://sre.google/sre-book/monitoring-distributed-systems/#xref_monitoring_golden-signals
• logerrors 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 pgMustard
• Nikolay Samokhvalov, founder of Postgres.ai

With 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-brennand
• Andrew Johnson https://postgres.fm/people/andrew-johnson
• Metronome https://metronome.com
• Root Cause Analysis: PostgreSQL MultiXact member exhaustion incidents (blog post by Metronome) https://metronome.com/blog/root-cause-analysis-postgresql-multixact-member-exhaustion-incidents-may-2025
• Multixacts and Wraparound (docs) https://www.postgresql.org/docs/current/routine-vacuuming.html#VACUUM-FOR-MULTIXACT-WRAPAROUND
• multixact.c source code https://github.com/postgres/postgres/blob/master/src/backend/access/transam/multixact.c
• Add 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-harmful
• vacuum_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.com
• Amazon 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#L31

And 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 pgMustard
• Nikolay Samokhvalov, founder of Postgres.ai

With 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-sougoumarane
• Supabase https://supabase.com
• Announcing Multigres https://supabase.com/blog/multigres-vitess-for-postgres
• Vitess https://github.com/vitessio/vitess
• SPQR https://github.com/pg-sharding/spqr
• Citus https://github.com/citusdata/citus
• PgDog https://github.com/pgdogdev/pgdog
• Myths and Truths about Synchronous Replication in PostgreSQL (talk by Alexander Kukushkin) https://www.youtube.com/watch?v=PFn9qRGzTMc
• Consensus algorithms at scale (8 part series by Sugu) https://planetscale.com/blog/consensus-algorithms-at-scale-part-1
• A More Flexible Paxos (blog post by Sugu) https://www.sougou.io/a-more-flexible-paxos
• libpg_query https://github.com/pganalyze/libpg_query
• PL/Proxy https://github.com/plproxy/plproxy
• PlanetScale Postgres Benchmarking https://planetscale.com/blog/benchmarking-postgres
• MultiXact 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 pgMustard
• Nikolay Samokhvalov, founder of Postgres.ai

With special thanks to:

• Jessie Draws for the elephant artwork