Postgres FM

Nikolay and Michael discuss heavyweight locks in Postgres — how to think about them, why you can't avoid them, and some tips for minimising issues. Here are some links to things they mentioned:Locking (docs) https://www.postgresql.org/docs/current/explicit-locking.htmlPostgres rocks, except when it blocks (blog post by Marco Slot) https://www.citusdata.com/blog/2018/02/15/when-postgresql-blocks/Lock Conflicts (tool by Hussein Nasser) https://pglocks.org/log_lock_waits (docs) https://www.postgresql.org/docs/current/runtime-config-logging.html#GUC-LOG-LOCK-WAITSHow to analyze heavyweight lock trees (guide by Nikolay) https://gitlab.com/postgres-ai/postgresql-consulting/postgres-howtos/-/blob/main/0042_how_to_analyze_heavyweight_locks_part_2.mdLock management (docs) https://www.postgresql.org/docs/current/runtime-config-locks.htmlOur episode on zero-downtime migrations https://postgres.fm/episodes/zero-downtime-migrations~~~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 ten dangerous Postgres related issues — ones that might be painful enough to get onto the CTO and even CEOs desk, and then what you can do proactively. The ten issues discussed are:Heavy lock contentionBloat control and index maintenance  Lightweight lock contentionTransaction ID wraparound4-byte integer PKs hitting the limitReplication limitsHard limitsData lossPoor HA choice (split brain)Corruption of various kindsSome previous episodes they mentioned that cover the issues in more detail: PgDog https://postgres.fm/episodes/pgdogPerformance cliffs https://postgres.fm/episodes/performance-cliffsZero-downtime migrations https://postgres.fm/episodes/zero-downtime-migrations Queues in Postgres https://postgres.fm/episodes/queues-in-postgresBloat https://postgres.fm/episodes/bloatIndex maintenance https://postgres.fm/episodes/index-maintenanceSubtransactions https://postgres.fm/episodes/subtransactionsFour million TPS https://postgres.fm/episodes/four-million-tpsTransaction ID wraparound https://postgres.fm/episodes/transaction-id-wraparoundpg_squeeze https://postgres.fm/episodes/pg_squeeze synchronous_commit https://postgres.fm/episodes/synchronous_commitManaged service support https://postgres.fm/episodes/managed-service-support And finally, some other things they mentioned: A great recent SQL Server-related podcast episode on tuning techniques https://kendralittle.com/2024/05/20/erik-darling-and-kendra-little-rate-sql-server-performance-tuning-techniques/Postgres Indexes, Partitioning and LWLock:LockManager Scalability (blog post by Jeremy Schneider) https://ardentperf.com/2024/03/03/postgres-indexes-partitioning-and-lwlocklockmanager-scalability/Do you vacuum everyday? (talk by Hannu Krosing) https://www.youtube.com/watch?v=JcRi8Z7rkPgpg_stat_wal https://pgpedia.info/p/pg_stat_wal.htmlThe benefit of lz4 and zstd for Postgres WAL compression (Small Datum blog, Mark Callaghan) https://smalldatum.blogspot.com/2022/05/the-benefit-of-lz4-and-zstd-for.htmlSplit-brain in case of network partition (CloudNativePG issue/discussion) https://github.com/cloudnative-pg/cloudnative-pg/discussions/7462 ~~~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 synchronous_commit — what it means on single node setups, for synchronous replication setups, and the pros and cons of the different options for each. Here are some links to things they mentioned:synchronous_commit https://www.postgresql.org/docs/current/runtime-config-wal.html#GUC-SYNCHRONOUS-COMMITsynchronous_commit history on pgPedia https://pgpedia.info/s/synchronous_commit.htmlPatroni’s maximum_lag_on_failover setting https://patroni.readthedocs.io/en/master/replication_modes.html#asynchronous-mode-durabilitywal_writer_delay https://www.postgresql.org/docs/current/runtime-config-wal.html#GUC-WAL-WRITER-DELAYSelective asynchronous commits in PostgreSQL - balancing durability and performance (blog post by Shayon Mukherjee) https://www.shayon.dev/post/2025/75/selective-asynchronous-commits-in-postgresql-balancing-durability-and-performance/Asynchronous Commit https://www.postgresql.org/docs/current/wal-async-commit.htmlsynchronous_standby_names https://www.postgresql.org/docs/current/runtime-config-replication.html#GUC-SYNCHRONOUS-STANDBY-NAMESJepson article about Amazon RDS multi-AZ clusters (by Kyle Kingsbury, aka "Aphyr”) https://jepsen.io/analyses/amazon-rds-for-postgresql-17.4~~~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 managed service support — some tips on how to handle cases that aren't going well, tips for requesting features, whether to factor in support when choosing service provider, and whether to use one at all. Here are some links to things they mentioned:YugabyteDB’s new upgrade framework https://www.yugabyte.com/blog/postgresql-upgrade-frameworkEpisode on Blue-green deployments https://postgres.fm/episodes/blue-green-deploymentspg_createsubscriber https://www.postgresql.org/docs/current/app-pgcreatesubscriber.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 and Michael discuss time-series considerations for Postgres — including when it matters, some tips for avoiding issues, performance considerations, and more. Here are some links to things they mentioned:Time series data https://en.wikipedia.org/wiki/Time_seriesTimescaleDB https://github.com/timescale/timescaledb13 Tips to Improve PostgreSQL Insert Performance https://www.timescale.com/blog/13-tips-to-improve-postgresql-insert-performanceWhy we're leaving the cloud (37 Signals / Basecamp / David Heinemeier Hansson) https://world.hey.com/dhh/why-we-re-leaving-the-cloud-654b47e0UUID v7 and partitioning (“how to” by Nikolay) https://gitlab.com/postgres-ai/postgresql-consulting/postgres-howtos/-/blob/main/0065_uuid_v7_and_partitioning_timescaledb.mdpg_cron https://github.com/citusdata/pg_cronpg_partman https://github.com/pgpartman/pg_partmanOur episode on BRIN indexes https://postgres.fm/episodes/brin-indexesTutorial from Citus (Andres Freund and Marco Slot) including rollups https://www.youtube.com/watch?v=0ybz6zuXCPoIoT with PostgreSQL (talk by Chris Ellis) https://youtube.com/watch?v=KnUoDBGv4aw&t=58pg_timeseries https://github.com/tembo-io/pg_timeseriesDuckDB https://duckdb.org~~~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 Tomas Vondra to discuss single query performance cliffs — what they are, why they happen, some things we can do to make them less likely or less severe, and some potential improvements to Postgres that could help. Here are some links to things they mentioned:Tomas Vondra https://postgres.fm/people/tomas-vondraWhere do performance cliffs come from? (Talk by Tomas) https://www.youtube.com/watch?v=UzdAelm-QSYWhere do performance cliffs come from? (Slides) https://vondra.me/pdf/performance-cliffs-posette-2024.pdfIncrease the number of fast-path lock slots (committed for Postgres 18) https://www.postgresql.org/message-id/flat/E1ss4gX-000IvX-63%40gemulon.postgresql.org San Francisco Bay Area Postgres meet-up with Tomas on 8th April (online) https://www.meetup.com/postgresql-1/events/306484787Our episode on Extended Statistics https://postgres.fm/episodes/extended-statisticsLogging plan of the currently running query (proposed patch by Rafael Thofehrn Castro and Atsushi Torikoshi) https://commitfest.postgresql.org/patch/5330Our episode with Peter Geoghegan on Skip Scan https://postgres.fm/episodes/skip-scanIndex Prefetching patch that Tomas is collaborating with Peter Geoghegan on https://commitfest.postgresql.org/patch/4351A generalized join algorithm, G-Join (paper by Goetz Graefe) https://dl.gi.de/server/api/core/bitstreams/ce8e3fab-0bac-45fc-a6d4-66edaa52d574/content Smooth Scan: Robust Access Path Selection without Cardinality Estimation (paper by R. Borovica, S. Idreos, A. Ailamaki, M. Zukowski, C. Fraser) https://stratos.seas.harvard.edu/sites/g/files/omnuum4611/files/stratos/files/smoothscan.pdfJust-in-Time Compilation (JIT) https://www.postgresql.org/docs/current/jit.htmlNotes from a pgconf.dev unconference session in 2024 about JIT (discusses issues) https://wiki.postgresql.org/wiki/PGConf.dev_2024_Developer_Unconference#JIT_compilationImplementing an alternative JIT provider for PostgreSQL (by Xing Guo) https://higuoxing.com/archives/implementing-jit-provider-for-pgsqlTomas’ Office Hours https://vondra.me/posts/office-hours-experiment ~~~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 Lev Kokotov to discuss PgDog — including whether or when sharding is needed, the origin story (via PgCat), what's already supported, and what's coming next.    Here are some links to things they mentioned:Lev Kokotov https://postgres.fm/people/lev-kokotovPgDog https://github.com/pgdogdev/pgdogPgCat https://github.com/postgresml/pgcatAdopting PgCat (Instacart blog post) https://www.instacart.com/company/how-its-made/adopting-pgcat-a-nextgen-postgres-proxyPgDog discussion on Hacker News https://news.ycombinator.com/item?id=43364668Citus https://github.com/citusdata/citusSharding & IDs at Instagram (blog post) https://instagram-engineering.com/sharding-ids-at-instagram-1cf5a71e5a5cSharding pgvector (blog post by Lev) https://pgdog.dev/blog/sharding-pgvector~~~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 talks Michael through using cloud snapshots — how they can be used to reduce RTO for huge Postgres setups, also to improve provisioning time, and some major catches to be aware of. Here are some links to things they mentioned:Snapshots on RDS https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_CreateSnapshot.htmlpgBackRest https://pgbackrest.orgWAL-G https://github.com/wal-g/wal-gpg_backup_start and pg_backup_stop (docs) https://www.postgresql.org/docs/current/functions-admin.html#FUNCTIONS-ADMIN-BACKUP How to troubleshoot long Postgres startup (by Nikolay) https://gitlab.com/postgres-ai/postgresql-consulting/postgres-howtos/-/blob/main/0003_how_to_troubleshoot_long_startup.mdRestoring to a DB instance (RDS docs mentioning lazy loading) https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_RestoreFromSnapshot.html Amazon EBS fast snapshot restore https://docs.aws.amazon.com/ebs/latest/userguide/ebs-fast-snapshot-restore.htmlOur 100th episode “To 100TB, and beyond!” https://postgres.fm/episodes/to-100tb-and-beyond ~~~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 GIN indexes in Postgres — what they are, what they're used for, and some limitations to be aware of. Here are some links to things they mentioned:GIN Indexes https://www.postgresql.org/docs/current/gin.htmlGeneralized Search Trees for Database Systems (Hellerstein, Naughton, Pfeffer) https://dsf.berkeley.edu/papers/vldb95-gist.pdf RUM extension https://pgxn.org/dist/rum/1.1.0/Understanding Postgres GIN Indexes: The Good and the Bad (Lukas Fittl) https://pganalyze.com/blog/gin-index~~~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 use a recent "best practices" article as a prompt — giving a few tips each on the topics mentioned, like schema design, performance, backups, and more. Here are some links to things they mentioned:7 Crucial PostgreSQL Best Practices (recent blog post) https://speakdatascience.com/postgresql-best-practices“Don't do this” episode https://postgres.fm/episodes/dont-do-thisArticle discussion on Hacker News https://news.ycombinator.com/item?id=42992913Mozilla’s SQL Style Guide https://docs.telemetry.mozilla.org/concepts/sql_style“SQL vs NoSQL” episode with Franck Pachot https://postgres.fm/episodes/sql-vs-nosqlHA episode https://postgres.fm/episodes/high-availability ~~~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