Postgres FM

With Nikolay taking a well-earned break, Michael covers the basics of EXPLAIN — what it is, the parameters available, and a process he recommends for using it. Here are some links to the things mentioned:EXPLAIN (docs) https://www.postgresql.org/docs/current/sql-explain.htmlUsing EXPLAIN (docs) https://www.postgresql.org/docs/current/using-explain.htmlEXPLAIN Explained (talk by Josh Berkus https://www.youtube.com/watch?app=desktop&v=mCwwFAl1pBUBeyond joins and indexes (slides from talk by Bruce Momjian) https://momjian.us/main/writings/pgsql/beyond.pdfDepesz https://explain.depesz.comDalibo https://explain.dalibo.compgMustard https://www.pgmustard.com/A beginners guide to explain (talk by Michael) https://www.youtube.com/watch?v=31EmOKBP1PY&t=24sExplain beyond the basics (talk by Michael) https://www.youtube.com/watch?v=sGkSOvuaPs4auto_explain episode https://postgres.fm/episodes/auto_explainRow estimates episode https://postgres.fm/episodes/row-estimatesSlow queries and slow transactions episode https://postgres.fm/episodes/slow-queries-and-slow-transactionsBenchmarking episode https://postgres.fm/episodes/benchmarkingEXPLAIN glossary by Michael (forgot to mention, oops!) https://www.pgmustard.com/docs/explain~~~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 brought to you by:Nikolay Samokhvalov, founder of Postgres.aiMichael Christofides, founder of pgMustardWith special thanks to:Jessie Draws for the amazing artwork 

Happy holidays! Today's topic is work_mem — how it's used and how to tune it. Related post: https://x.com/samokhvalov/status/1740813478150189172?s=46&t=HSxrW86NZqzPQP9vXVJEWg.

Nikolay and Michael discuss partitioning by ULID — revisiting some of the old UUID vs bigint key debate in light of some new UUID specs, and how these can be used for partitioning (by time).  Here are some links to things they mentioned:Nikolay’s episode on UUID (for primary keys) https://postgres.fm/episodes/uuid Postgres TV hacking session with Andrey and Kirk: https://www.youtube.com/watch?v=YPq_hiOE-N8UUIDv7 patch https://commitfest.postgresql.org/43/4388/ Use ULID Idempotency Keys (tip 6 in this blog post from Shopify) https://shopify.engineering/building-resilient-payment-systems Nikolay’s howto post on UUID v7 and partitioning with TimescaleDB https://gitlab.com/postgres-ai/postgresql-consulting/postgres-howtos/-/blob/main/0065_uuid_v7_and_partitioning_timescaledb.md Hussein Nasser’s YouTube video about the above https://www.youtube.com/watch?v=f53-Iw_5ucA UUID proposal that includes UUIDv7 and UUIDv8 (work in progress): https://datatracker.ietf.org/doc/draft-ietf-uuidrev-rfc4122bis/history/  James Blackwood-Sewell advice on more elegant solution using TimescaleDB https://twitter.com/jamessewell/status/1730125437903450129 ULIDs and Stripe IDs (section of Identity Crisis blog post by Brandur) https://brandur.org/nanoglyphs/026-ids#ulids Crunchy Bridge changed their default random_page_cost to 1.1 🙌 https://twitter.com/brandur/status/1720477470116422028 UUIDs vs serials for keys (newer post from Christophe Pettus) https://thebuild.com/blog/2023/02/16/uuids-vs-serials-for-keys/ ~~~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 brought to you by:Nikolay Samokhvalov, founder of Postgres.aiMichael Christofides, founder of pgMustardWith special thanks to:Jessie Draws for the amazing artwork 

Nikolay and Michael discuss hash indexes in Postgres — what they are, some brief history, their pros and cons vs btrees, and whether or when they recommend using them.Update: the idea Nikolay mentioned at the end of this episode turns out to be a little fraught (and as such, inadvisable).  Here are some links to things they mentioned:Index types (docs) https://www.postgresql.org/docs/current/indexes-types.html  Re-introducing hash indexes in PostgreSQL (blog post by Haki Benita and Michael) https://hakibenita.com/postgresql-hash-index Hash indexes intro (docs) https://www.postgresql.org/docs/current/hash-intro.html Hash indexes implementation (docs) https://www.postgresql.org/docs/current/hash-implementation.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 brought to you by:Nikolay Samokhvalov, founder of Postgres.aiMichael Christofides, founder of pgMustardWith special thanks to:Jessie Draws for the amazing artwork 

Nikolay and Michael discuss PostgreSQL constraints — the six different types we have, how to add and modify them, including on large tables with high TPS.  Here are some links to things they mentioned:Constraints (docs) https://www.postgresql.org/docs/current/ddl-constraints.htmlUnique index vs unique constraint issue (2017) https://www.postgresql.org/message-id/flat/CANNMO%2B%2B7%2BuVMj%2BZPGKB_zuRpKE0sNthy2Z-_oKSS%3DoE3_rN7QA%40mail.gmail.com Our episode on NULLs https://postgres.fm/episodes/nulls-the-good-the-bad-the-ugly-and-the-unknownAdvanced Int to Bigint Conversions (talk by Robert Treat) https://www.youtube.com/watch?v=_IieyXzdmcM Use BIGINT in Postgres (blog post by Ryan Lambert) https://blog.rustprooflabs.com/2021/06/postgres-bigint-by-default How to add a foreign key (Tweet by Nikolay) https://twitter.com/samokhvalov/status/1732056107483636188 Bloat, pg_repack, and deferred constraints (blog post by Nikolai Averin from Miro) https://medium.com/miro-engineering/postgresql-bloat-pg-repack-and-deferred-constraints-d0ecf33337ec ~~~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 brought to you by:Nikolay Samokhvalov, founder of Postgres.aiMichael Christofides, founder of pgMustardWith special thanks to:Jessie Draws for the amazing artwork 

Nikolay and Michael discuss PostgreSQL events — whether in-person or online, large conferences or small meet-ups, as well as some strong opinions based on their experiences attending, speaking, and organising them.  Here are some links to things they mentioned:PGSQL Phriday #014: PostgreSQL Events https://www.cybertec-postgresql.com/en/pgsql-phriday-014-postgresql-events/ PGCon https://www.pgcon.org/ Highload https://highload.rs/ The San Francisco Bay Area PostgreSQL Meetup Group https://www.meetup.com/postgresql-1/ Our episode on “Why is Postgres popular?” https://postgres.fm/episodes/why-is-postgres-popular PGConf EU https://pgconf.eu/ Open talks series on Postgres TV https://www.youtube.com/playlist?list=PLH8y1BNPAKjJCuZiDRl0qUEDaKLBpFvZ9 Rails World (including videos!) https://rubyonrails.org/world Upcoming events https://www.postgresql.org/about/events/ ~~~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 brought to you by:Nikolay Samokhvalov, founder of Postgres.aiMichael Christofides, founder of pgMustardWith special thanks to:Jessie Draws for the amazing artwork 

Nikolay and Michael discuss PostgreSQL subtransactions — what they are, and four issues they can cause at scale.  Here are some links to things they mentioned:Subtransactions (docs) https://www.postgresql.org/docs/current/subxacts.html  SAVEPOINT (docs) https://www.postgresql.org/docs/current/sql-savepoint.html  PostgreSQL Subtransactions Considered Harmful (blog post by Nikolay) https://postgres.ai/blog/20210831-postgresql-subtransactions-considered-harmful  Subtransactions and performance in PostgreSQL (blog post by Laurenz at Cybertec) https://www.cybertec-postgresql.com/en/subtransactions-and-performance-in-postgresql/  Notes on some PostgreSQL implementation details (blog post by Nelson Elhage) https://buttondown.email/nelhage/archive/notes-on-some-postgresql-implementation-details/ Why we spent the last month eliminating PostgreSQL subtransactions (GitLab blog post) https://about.gitlab.com/blog/2021/09/29/why-we-spent-the-last-month-eliminating-postgresql-subtransactions/  ~~~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 brought to you by:Nikolay Samokhvalov, founder of Postgres.aiMichael Christofides, founder of pgMustardWith special thanks to:Jessie Draws for the amazing artwork 

Nikolay and Michael discuss companion databases — when and why you might want to add another database management system to your stack (or not), and some specifics for analytics, timeseries, search, and vectors.  Here are some links to things they mentioned:Heap were using Postgres + Citus for analytics as of 2022 https://www.heap.io/blog/juggling-state-machines-incident-response-and-data-soup-a-glimpse-into-heaps-engineering-culture Heap recently moved their core analytics to SingleStore (we only spotted this after recording 🤦‍♂️) https://www.heap.io/blog/heaps-next-generation-data-platform Posthog moved their analytics from Postgres to Clickhouse https://posthog.com/blog/clickhouse-vs-postgres Timescale https://www.timescale.com/ Citus https://www.citusdata.com/ Hydra https://www.hydra.so/ Our episode on real-time analytics https://postgres.fm/episodes/real-time-analytics Our episode on queues https://postgres.fm/episodes/queues-in-postgres Our episode on logical replication https://postgres.fm/episodes/logical-replication Full Text Search in PostgreSQL (docs) https://www.postgresql.org/docs/current/textsearch.html ZomboDB https://www.zombodb.com/ ParadeDB https://www.paradedb.com/ PeerDB https://www.peerdb.io/ RUM indexes https://github.com/postgrespro/rum Debezium https://debezium.io/ pgmq https://github.com/tembo-io/pgmq Tembo https://tembo.io/ pgvector vs Pinecone (Supabase blog post) https://supabase.com/blog/pgvector-vs-pinecone Jepsen analyses https://jepsen.io/analyses ~~~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 brought to you by:Nikolay Samokhvalov, founder of Postgres.aiMichael Christofides, founder of pgMustardWith special thanks to:Jessie Draws for the amazing artwork 

Nikolay and Michael discuss blue-green deployments — specifically an RDS blog post, how similar this is (or not) to what they understand to be blue-green deployments, and how applicable the methodology might be in the database world more generally.  Here are some links to things they mentioned:Fully managed Blue/Green Deployment in Amazon Aurora PostgreSQL and Amazon RDS for PostgreSQL https://aws.amazon.com/blogs/database/new-fully-managed-blue-green-deployment-in-amazon-aurora-postgresql-and-amazon-rds-for-postgresql/  Blue-green deployment (blog post by Martin Fowler) https://martinfowler.com/bliki/BlueGreenDeployment.html  Our episode on logical replication https://postgres.fm/episodes/logical-replication pgroll https://github.com/xataio/pgroll ~~~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 brought to you by:Nikolay Samokhvalov, founder of Postgres.aiMichael Christofides, founder of pgMustardWith special thanks to:Jessie Draws for the amazing artwork 

Nikolay and Michael discuss data model trade-offs — some cases where you might want to (gasp) de-normalize, and which PostgreSQL internals are at play.  Here are some links to things they mentioned:Our episode on JSON https://postgres.fm/episodes/json PostgreSQL limits https://www.postgresql.org/docs/current/limits.htmlBoyce–Codd normal form https://en.wikipedia.org/wiki/Boyce–Codd_normal_form Our episode on over-indexing https://postgres.fm/episodes/over-indexing Heap-Only Tuples (HOT) optimisation https://www.postgresql.org/docs/current/storage-hot.html The Surprising Impact of Medium-Size Texts on PostgreSQL Performance https://hakibenita.com/sql-medium-text-performance Query planner settings (collapse limits and Genetic Query Optimizer) https://www.postgresql.org/docs/current/runtime-config-query.html WITH Queries (Common Table Expressions) https://www.postgresql.org/docs/current/queries-with.html Our episode on benchmarking https://postgres.fm/episodes/benchmarking The tests and benchmarks Nikolay mentioned https://gitlab.com/postgres-ai/postgresql-consulting/tests-and-benchmarks/-/issues~~~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 brought to you by:Nikolay Samokhvalov, founder of Postgres.aiMichael Christofides, founder of pgMustardWith special thanks to:Jessie Draws for the amazing artwork