Postgres FM

Nikolay and Michael discuss some more advanced topics around EXPLAIN, including some tips for complex query plans, some recent improvements, and an idea or two that might make it even better. Here are some links to things they mentioned:Michael’s solo episode on EXPLAIN basics https://postgres.fm/episodes/explainOur episode on auto_explain https://postgres.fm/episodes/auto_explainWhich cloud providers support auto_explain? (Blog post by Michael) https://www.pgmustard.com/blog/which-cloud-providers-support-auto-explainpsychopg https://www.psycopg.orgOur first episode on BUFFERS https://postgres.fm/episodes/buffers-by-defaultOur second episode on BUFFERS https://postgres.fm/episodes/buffers-ii-the-sequeltrack_io_timing https://www.postgresql.org/docs/current/runtime-config-statistics.html#GUC-TRACK-IO-TIMINGcompute_query_id https://www.postgresql.org/docs/current/runtime-config-statistics.html#GUC-COMPUTE-QUERY-ID EXPLAIN: beyond the basics (talk by Michael) https://www.youtube.com/watch?v=sGkSOvuaPs4~~~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 

Michael and Nikolay are joined by Alexander Kukushkin, PostgreSQL contributor and maintainer of Patroni, to discuss all things Patroni — what it is, how it works, recent improvements, and more.Here are some links to things they mentioned:Alexander Kukushkin https://postgres.fm/people/alexander-kukushkinPatroni https://github.com/patroni/patroniSpilo https://github.com/zalando/spilo Zalando Postgres Operator https://github.com/zalando/postgres-operatorCrunchy Data Postgres Operator https://github.com/CrunchyData/postgres-operatorSplit-brain https://en.wikipedia.org/wiki/Split-brain_(computing)repmgr https://github.com/EnterpriseDB/repmgrCloudNativePG https://github.com/cloudnative-pg/cloudnative-pgPatroni release notes https://patroni.readthedocs.io/en/latest/releases.htmlCitus & Patroni talk and demo by Alexander (at Citus Con 2023) https://www.youtube.com/watch?v=Mw8O9d0ez7E~~~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 discuss the fresh new Postgres 17 release! They cover several performance improvements, favourite new features, and some considerations for upgrading. Here are some links to things they mentioned:Postgres 17 release notes https://www.postgresql.org/docs/17/release-17.htmltransaction_timeout episode https://postgres.fm/episodes/transaction_timeoutVACUUM improvements discussed towards end of episode with Melanie Plageman https://postgres.fm/episodes/getting-started-with-benchmarkingB-tree improvements discussed in episdode with Peter Geoghegan https://postgres.fm/episodes/skip-scanAs Rails developers, why we are excited about PostgreSQL 17 (blog post by Benoit Tigeot) https://benoittgt.github.io/blog/postgres_17_rails/ Real World Performance Gains With Postgres 17 B-tree Bulk Scans (blog post by Brandur Leach) https://www.crunchydata.com/blog/real-world-performance-gains-with-postgres-17-btree-bulk-scansMERGE RETURNING came up towards end of episode with Haki Benita https://postgres.fm/episodes/get-or-createuuid_extract_timestamp and uuid_extract_version functions https://www.postgresql.org/docs/current/functions-uuid.htmlEpisode on UUID https://postgres.fm/episodes/uuidPartitioning by ULID https://postgres.fm/episodes/partitioning-by-ulidWhy Upgrade? (site by depesz) https://why-upgrade.depesz.comWhy 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-subtransactionsSynchronization of sequences to subscriber (patch that needs review!)  https://commitfest.postgresql.org/49/5111~~~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 discuss planning time in Postgres — what it is, how to spot issues, its relationship to things like partitioning, and some tips for avoiding issues. Here are some links to things they mentioned:Query Planning (docs) https://www.postgresql.org/docs/current/runtime-config-query.htmlAre there limits to partition counts? (Blog post by depesz) https://www.depesz.com/2021/01/17/are-there-limits-to-partition-countsNikolays recent experiment https://postgres.ai/chats/01920004-a982-7896-b8cb-dfd2406359b0PgBouncer now supports prepared statements https://github.com/pgbouncer/pgbouncer/releases/tag/pgbouncer_1_21_0“The year of the lock manager’s revenge” (from blog post by Jeremy Schneider) https://ardentperf.com/2024/03/03/postgres-indexes-partitioning-and-lwlocklockmanager-scalabilitypg_stat_statements.track_planning https://www.postgresql.org/docs/current/pgstatstatements.html#id-1.11.7.42.9.2.4.1.3pg_hint_plan https://github.com/ossc-db/pg_hint_plan~~~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 discuss why counting can be slow in Postgres, and what the options are for counting things quickly at scale. Here are some links to things they mentioned:Aggregate functions (docs) https://www.postgresql.org/docs/current/functions-aggregate.htmlPostgREST https://github.com/PostgREST/postgrest Get rid of count by default in PostgREST https://github.com/PostgREST/postgrest/issues/273 Faster PostgreSQL Counting (by Joe Nelson on the Citus blog) https://www.citusdata.com/blog/2016/10/12/count-performance Our episode on Index-Only Scans https://postgres.fm/episodes/index-only-scansPostgres HyperLogLog https://github.com/citusdata/postgresql-hllOur episode on Row estimates https://postgres.fm/episodes/row-estimates Our episode about dangers of NULLs https://postgres.fm/episodes/nulls-the-good-the-bad-the-ugly-and-the-unknown Aggregate expressions, including FILTER https://www.postgresql.org/docs/current/sql-expressions.html#SYNTAX-AGGREGATESSpread writes for counter cache (tip from Tobias Petry) https://x.com/tobias_petry/status/1475870220422107137pg_ivm extension (Incremental View Maintenance) https://github.com/sraoss/pg_ivm pg_duckdb announcement https://motherduck.com/blog/pg_duckdb-postgresql-extension-for-duckdb-motherduckOur episode on Queues in Postgres https://postgres.fm/episodes/queues-in-postgresOur episode on Real-time analytics https://postgres.fm/episodes/real-time-analyticsClickHouse acquired PeerDB https://clickhouse.com/blog/clickhouse-acquires-peerdb-to-boost-real-time-analytics-with-postgres-cdc-integrationTimescale Continuous Aggregates https://www.timescale.com/blog/materialized-views-the-timescale-wayTimescale editions https://docs.timescale.com/about/latest/timescaledb-editionsLoose indexscan https://wiki.postgresql.org/wiki/Loose_indexscan~~~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 

Michael and Nikolay are joined by Peter Geoghegan, major contributor and committer to Postgres, to discuss adding skip scan support to PostgreSQL over versions 17 and 18. Here are some links to things they mentioned:Peter Geoghegan https://postgres.fm/people/peter-geogheganPeter’s previous (excellent) interview on Postgres TV https://www.youtube.com/watch?v=iAPawr1DxhMEfficient Search of Multidimensional B-Trees (1995 paper by Harry Leslie, Rohit Jain, Dave Birdsall, and Hedieh Yaghmai) https://vldb.org/conf/1995/P710.PDFIndex Skip Scanning in Oracle https://oracle-base.com/articles/9i/index-skip-scanningPeter’s introductory email to the hackers mailing list about adding skip scan https://www.postgresql.org/message-id/CAH2-Wzmn1YsLzOGgjAQZdn1STSG_y8qP__vggTaPAYXJP+G4bw@mail.gmail.comLoose Indexscan versus Index Skip Scan (PostgreSQL wiki) https://wiki.postgresql.org/wiki/Loose_indexscanTom Lane will be on the Talking Postgres podcast on October 9th https://aka.ms/TalkingPostgres-Ep20-calBenoit Tigeot feedback and repro (originally reported via Slack) https://gist.github.com/benoittgt/ab72dc4cfedea2a0c6a5ee809d16e04d?permalink_comment_id=4597410#gistcomment-4597410Summary video and blog post about the v17 work by Lukas from pganalyze (not mentioned but great) https://pganalyze.com/blog/5mins-postgres-17-faster-btree-index-scansUnderstanding HNSW + filtering (pgvector repo discussion) https://github.com/pgvector/pgvector/issues/259btree_gin https://www.postgresql.org/docs/current/btree-gin.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 special thanks to:Jessie Draws for the elephant artwork 

Nikolay and Michael discuss PostgreSQL emergencies — both the psychological side of incident management, and some technical aspects too. Here are some links to things they mentioned:Site Reliability Engineering resources from Google https://sre.googleGitLab Handbook SRE https://handbook.gitlab.com/job-families/engineering/infrastructure/site-reliability-engineerKeeping Customers Streaming — The Centralized Site Reliability Practice at Netflix https://netflixtechblog.com/keeping-customers-streaming-the-centralized-site-reliability-practice-at-netflix-205cc37aa9fbOur monitoring checklist episode https://postgres.fm/episodes/monitoring-checklistHannu Krosing talk on Postgres TV — Do you vacuum everyday? https://www.youtube.com/watch?v=JcRi8Z7rkPgOur episode on corruption https://postgres.fm/episodes/corruptionNikolay’s episode on stopping and starting Postgres faster https://postgres.fm/episodes/stop-and-start-postgres-fasterOur episode on out of disk https://postgres.fm/episodes/out-of-diskThe USE method (Brendan Gregg) https://www.brendangregg.com/usemethod.html Thundering herd problem https://en.wikipedia.org/wiki/Thundering_herd_problempgwatch2 Postgres AI edition https://gitlab.com/postgres-ai/pgwatch2~~~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 

Michael and Nikolay are joined by Haki Benita, a technical lead and database enthusiast who writes an excellent blog and gives popular talks and training sessions too, to discuss the surprisingly complex topic of trying to implement “get or create” in PostgreSQL — handling issues around idempotency, concurrency, and bloat. Here are some links to things they mentioned:Haki Benita https://hakibenita.com How to Get or Create in PostgreSQL (blog post by Haki) https://hakibenita.com/postgresql-get-or-create "Find-or-insert" using a single query (how-to guide by Nikolay) https://gitlab.com/postgres-ai/postgresql-consulting/postgres-howtos/-/blob/main/0036_find-or-insert_using_a_single_query.md?ref_type=heads Is SELECT or INSERT in a function prone to race conditions? (Answer by Erwin Brandstetter)  https://stackoverflow.com/questions/15939902/is-select-or-insert-in-a-function-prone-to-race-conditions/15950324#15950324 get_or_create() in Django https://docs.djangoproject.com/en/5.1/ref/models/querysets/#get-or-create Subtransactions Considered Harmful (blog post by Nikolay) https://postgres.ai/blog/20210831-postgresql-subtransactions-considered-harmful MERGE (Postgres documentation) https://www.postgresql.org/docs/current/sql-merge.htmlHidden dangers of duplicate key violations in PostgreSQL and how to avoid them (blog post by Divya Sharma and Shawn McCoy from the RDS team) https://aws.amazon.com/blogs/database/hidden-dangers-of-duplicate-key-violations-in-postgresql-and-how-to-avoid-them/ One, Two, Skip a Few... (blog post by Pete Hamilton from Incident) https://incident.io/blog/one-two-skip-a-few ~~~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 

Michael and Nikolay are joined by Melanie Plageman, database internals engineer at Microsoft and major contributor and committer to PostgreSQL, to discuss getting started with benchmarking — how it differs for users and developers of Postgres, how and when it comes up during development, some tools and lessons, as well as what she's working on at the moment. Here are some links to things they mentioned:Melanie Plageman https://postgres.fm/people/melanie-plagemanMeanie’s Introduction to Benchmarking With pgbench talk slides https://postgresql.us/events/pgconfnyc2023/schedule/session/1410-introduction-to-benchmarking-with-pgbench/#slidesMelanie’s Visualizing Postgres I/O Performance for Development talk recording https://www.youtube.com/watch?v=CxyPZHG5beIMelanie’s Visualizing Postgres I/O Performance for Development talk slides https://speakerdeck.com/melanieplageman/o-performance-for-developmentpgbench https://www.postgresql.org/docs/current/pgbench.htmlMark Callaghan’s blog https://smalldatum.blogspot.comSome of Tomas Vondra’s blog posts https://www.enterprisedb.com/blog/author/tomas-vondraSome of Andres Freund’s blog posts https://www.citusdata.com/blog/authors/andres-freund/An example of Alexander Lakhin’s work https://www.postgresql.org/message-id/b32bed1b-0746-9b20-1472-4bdc9ca66d52%40gmail.comSimplifying the TPC Benchmark C, an OLTP Workload (talk by Mark Wong) https://www.youtube.com/watch?v=qi0I74urLoYMatplotlib https://matplotlib.orgpandas https://pandas.pydata.orgpg_stat_io https://www.postgresql.org/docs/current/monitoring-stats.html#MONITORING-PG-STAT-IO-VIEWpg_stat_io commit https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=a9c70b46dbe152e094f137f7e6ba9cd3a638ee25 pg_buffercache https://www.postgresql.org/docs/current/pgbuffercache.htmltmpfs https://docs.kernel.org/filesystems/tmpfs.htmlEager page freeze criteria mailing list thread https://www.postgresql.org/message-id/CAAKRu_b3tpbdRPUPh1Q5h35gXhY%3DspH2ssNsEsJ9sDfw6%3DPEAg%40mail.gmail.comThe path to using AIO in postgres (talk by Andres Freund) https://www.youtube.com/watch?v=qX50xrHwQa4Improve dead tuple storage for lazy vacuum (Masahiko Sawada) https://www.postgresql.org/message-id/flat/CAD21AoAfOZvmfR0j8VmZorZjL7RhTiQdVttNuC4W-Shdc2a-AA@mail.gmail.com~~~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 discuss Index-Only Scans in Postgres — what they are, how they help, some things to look out for, and some advice. Here are some links to things they mentioned:Index-Only Scans and Covering Indexes (docs) https://www.postgresql.org/docs/current/indexes-index-only-scans.htmlDiscussion on Twitter about JIT and Parallel Query defaults https://x.com/jer_s/status/1819749688184373742Postgres Wiki on Index-Only Scans https://wiki.postgresql.org/wiki/Index-only_scansHeap Fetches https://www.pgmustard.com/docs/explain/heap-fetchesRows Removed By Filter https://www.pgmustard.com/docs/explain/rows-removed-by-filterrandom_page_cost https://postgresqlco.nf/doc/en/param/random_page_cost/pg_dump docs change https://x.com/samokhvalov/status/1820539826363588755Crunchy Bridge changed random_page_cost to 1.1 for new servers https://docs.crunchybridge.com/changelog#postgres_random_page_cost_1_1Autovacuum Tuning Basics (updated blog post by Tomas Vondra) https://www.enterprisedb.com/blog/autovacuum-tuning-basicsOur episode on over-indexing https://postgres.fm/episodes/over-indexingOur episode on HOT updates https://postgres.fm/episodes/hot-updatesOur episode on partitioning https://postgres.fm/episodes/partitioning~~~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