Show Notes
Nik and Michael discuss the concept of gapless sequences — when you might want one, why sequences in Postgres can have gaps, and an idea or two if you do want them. And one quick clarification: changing the CACHE option in CREATE SEQUENCE can lead to even more gaps, the docs mention it explicitly.
Here are some links to things they mentioned: CREATE SEQUENCE https://www.postgresql.org/docs/current/sql-createsequence.html Sequence Manipulation Functions https://www.postgresql.org/docs/current/functions-sequence.html One, Two, Skip a Few (post by Pete Hamilton from Incident io) https://incident.io/blog/one-two-skip-a-few Postgres sequences can commit out-of-order (blog post by Anthony Accomazzo / Sequin) https://blog.sequinstream.com/postgres-sequences-can-commit-out-of-order Logical Replication of sequences (hackers thread) https://www.postgresql.org/message-id/flat/CAA4eK1LC%2BKJiAkSrpE_NwvNdidw9F2os7GERUeSxSKv71gXysQ%40mail.gmail.com Synchronization of sequences to subscriber (patch entry in commitfest) https://commitfest.postgresql.org/patch/5111/ Get or Create (episode with Haki Benita) https://postgres.fm/episodes/get-or-create German tank problem https://en.wikipedia.org/wiki/German_tank_problem
~~~ 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
More from Postgres FM
Nik is joined by Kirk Wolak, Software Architect at KiraSoft, to discuss what a database still needs after pg_restore finishes and before it takes production traffic — what pg_dump and pg_restore leave behind, why autovacuum may not catch up in time, and how Postgres itself could do better.
Nik and Michael are joined by Álvaro Hernández to discuss sharding Postgres with Citus and StackGres, especially the new query router support that has been added very recently.
Nik and Michael are joined by Salma El-Sayed and Kirk Wolak to discuss their in-progress and very ambitious Google Summer of Code project around adding Btree Merge support to Postgres.
Nik and Michael are joined by Sai Srirampur to discuss ClickHouse's new managed Postgres service.
Nik and Michael discuss hot_standby_feedback — what it controls, whether and when read replicas should be changed to on, and other settings you can change to help too.