Postgres FM

Nik and Michael discuss a listener question about archiving a database. Here are some links to things they mentioned: Listener request to talk about archiving https://www.youtube.com/watch?v=KFRK8PiIvTg&lc=UgyiFrO37gEgUaVhRgN4AaABAg Our episode on “Is pg_dump a backup tool?” https://postgres.fm/episodes/is-pg_dump-a-backup-tool ~~~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

Nik and Michael discuss max_connections, especially in the context of increasing it to solve problems like migrations intermittently failing(!) Here are some links to things they mentioned: max_connections https://www.postgresql.org/docs/current/runtime-config-connection.html#GUC-MAX-CONNECTIONSTweet about deployments vs connections issue https://x.com/brankopetric00/status/1991394329886077090Nik tweet in response https://x.com/samokhvalov/status/1991465573684027443Analyzing the Limits of Connection Scalability in Postgres (blog post by Andres Freund) https://www.citusdata.com/blog/2020/10/08/analyzing-connection-scalability/Exponential Backoff And Jitter (blog post by Marc Brooker) https://aws.amazon.com/blogs/architecture/exponential-backoff-and-jitter/~~~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

Nik and Michael discuss the various changes to EXPLAIN that arrived in Postgres 18. Here are some links to things they mentioned: EXPLAIN (official docs) https://www.postgresql.org/docs/current/sql-explain.htmlUsing EXPLAIN (official docs) https://www.postgresql.org/docs/current/using-explain.html EXPLAIN glossary (pgMustard site) https://www.pgmustard.com/docs/explainPostgres 18 release notes https://www.postgresql.org/docs/release/18.0/Enable BUFFERS with EXPLAIN ANALYZE by default (commit) https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=c2a4078ebOur (first) BUFFERS by default episode https://postgres.fm/episodes/buffers-by-default Show index search count in EXPLAIN ANALYZE (commit) https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=0fbceae841cb5a31b13d3f284ac8fdd19822ecebOur episode on Skip scan with Peter Geoghegan https://postgres.fm/episodes/skip-scanWhat do the new Index Searches lines in EXPLAIN mean? https://www.pgmustard.com/blog/what-do-index-searches-in-explain-meanpg_stat_plans presentation by Lukas Fittl https://www.youtube.com/watch?v=26coQV3f-wkImprove EXPLAIN's display of window functions (commit) https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=8b1b34254Show Parallel Bitmap Heap Scan worker stats in EXPLAIN ANALYZE (commit) https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=5a1e6df3bAdd information about WAL buffers being full (commit) https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=320545bfc ~~~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

Nik talks Michael through a recent benchmark he worked with Maxim Boguk on, to see how quickly they could provision a replica. Here are some links to things they mentioned:Ultra-fast replica creation with pgBackRest (blog post by Maxim Boguk and Nik) https://postgres.ai/blog/20251105-postgres-marathon-2-012-ultra-fast-replica-creation-pgbackrestCopying a database episode https://postgres.fm/episodes/copying-a-databaseAdd snapshot backup support for PostgreSQL in wal-g (draft PR by Andrey Borodin) https://github.com/wal-g/wal-g/pull/2101Multi-threaded pg_basebackup discussion 1: https://www.postgresql.org/message-id/flat/CAEHH7R4%3D_GN%2BLSsj0YZOXZ13yc%3DGk9umJOLNopjS%3DimK0c1mWA%40mail.gmail.comMulti-threaded pg_basebackup discussion 2: https://www.postgresql.org/message-id/flat/io_method https://www.postgresql.org/docs/current/runtime-config-resource.html#GUC-IO-METHOD pgBackRest https://github.com/pgbackrest/pgbackrestAdd sequence synchronization for logical replication (commit) https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=5509055d6956745532e65ab218e15b99d87d66ce Allow process priority to be set (pgBackRest feature added by David Steele) https://github.com/pgbackrest/pgbackrest/pull/2693 Hard limit on process-max (pgBackRest issue from 2019) https://github.com/pgbackrest/pgbackrest/issues/696 ~~~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

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.htmlSequence Manipulation Functions https://www.postgresql.org/docs/current/functions-sequence.htmlOne, Two, Skip a Few (post by Pete Hamilton from Incident io) https://incident.io/blog/one-two-skip-a-fewPostgres sequences can commit out-of-order (blog post by Anthony Accomazzo / Sequin) https://blog.sequinstream.com/postgres-sequences-can-commit-out-of-orderLogical Replication of sequences (hackers thread) https://www.postgresql.org/message-id/flat/CAA4eK1LC%2BKJiAkSrpE_NwvNdidw9F2os7GERUeSxSKv71gXysQ%40mail.gmail.comSynchronization 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-createGerman 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 pgMustardNikolay Samokhvalov, founder of Postgres.aiWith credit to:Jessie Draws for the elephant artwork