Nikolay and Michael discuss foreign keys in Postgres — what they are, their benefits, their overhead, some edge cases to be aware of, some improvements coming, and whether or not they generally recommend using them. Here are some links to things they mentioned: Foreign keys (docs) https://www.postgresql.org/docs/current/ddl-constraints.html#DDL-CONSTRAINTS-FKOur episode about constraints: https://postgres.fm/episodes/constraintsGitLab migration helper add_concurrent_foreign_key https://github.com/gitlabhq/gitlabhq/blob/master/rubocop/cop/migration/add_concurrent_foreign_key.rbAdding a foreign key without downtime (tweet by Nikolay) https://x.com/samokhvalov/status/1732056107483636188Bloat, pg_repack, and deferred constraints (blog post by Miro) https://medium.com/miro-engineering/postgresql-bloat-pg-repack-and-deferred-constraints-d0ecf33337ecPostgres 17 draft release notes, server configuration section https://www.postgresql.org/docs/17/release-17.html#RELEASE-17-SERVER-CONFIGOur 100th episode https://postgres.fm/episodes/to-100tb-and-beyondStop! Trigger Time (blog post by Michael) https://www.pgmustard.com/blog/trigger-timeShould I Create an Index on Foreign Keys? (Blog post by Percona) https://www.percona.com/blog/should-i-create-an-index-on-foreign-keys-in-postgresqlAvoid Postgres performance cliffs with MultiXact IDs and foreign keys (5 min video by Lukas Fittl) https://pganalyze.com/blog/5mins-postgres-multiXact-ids-foreign-keys-performanceExperiment to see basic overhead of foreign keys https://v2.postgres.ai/chats/01902ee6-8ed1-70ec-9345-5606305012f4Experiment showing an extreme contention case https://v2.postgres.ai/chats/018fb28d-865f-788d-adb7-efa7ed3a48c4Subtransactions Considered Harmful (blog post by Nikolay) https://postgres.ai/blog/20210831-postgresql-subtransactions-considered-harmfulNotes on some PostgreSQL implementation details (blog post by Nelson Elhage that mentions “subtransactions are cursed”) https://buttondown.email/nelhage/archive/notes-on-some-postgresql-implementation-details ~~~ 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