--- title: "The different types of log sequence numbers" publication: "Postgres Weekly" issue: 611 published_at: "2025-08-07" canonical_url: "https://postgresweekly.com/issues/611" --- Plus a lot of Postgres events news, and we're taking a week off. | #โ€‹611 โ€” August 7, 2025 [Web Version](https://postgresweekly.com/issues/611) โ˜€๏ธ **We're taking next week off,** so this will be the last issue until Thursday, August 21. Just a little summer vacation! ๐Ÿ˜… __ _Peter Cooper, your editor_ Together with [![Redgate\](https://res.cloudinary.com/cpress/image/upload/c_fill,g_auto,w_800,h_192/e_make_transparent/co_white,e_outline:9/juuaxaie2hv6pua7rl7k.png)](https://www.red-gate.com/) Postgres Weekly [![\](https://res.cloudinary.com/cpress/image/upload/w_1280,e_sharpen:60,q_auto/rjikvpj3fqkuniwzqb6n.jpg)](https://www.morling.dev/blog/postgres-replication-slots-confirmed-flush-lsn-vs-restart-lsn/) [Postgres Replication Slots: Confirmed Flush LSN vs. Restart LSN](https://www.morling.dev/blog/postgres-replication-slots-confirmed-flush-lsn-vs-restart-lsn/) โ€” Replication slots keep Postgres from discarding WAL (Write-Ahead Log) segments till all consumers have read them. Consumers track progress via log sequence numbers (LSNs), but Postgres exposes multiple LSNs with subtly different meanings. Gunnar Morling explains their differences, as well as why both matter in production. Gunnar Morling [![\](https://res.cloudinary.com/cpress/image/upload/c_limit,w_480,h_480,q_auto/copm/a88f0531.png)](https://www.red-gate.com/products/redgate-pgcompare/) [Spot and Fix PostgreSQL Schema Drift Fast](https://www.red-gate.com/products/redgate-pgcompare/) โ€” Tired of schema surprises? pgCompare shows you exactly what changed between environments, down to the SQL line. Quickly generate scripts to sync changes and fix issues fast. Available free for non-commercial use. [Check it out](https://www.red-gate.com/products/redgate-pgcompare/). Redgate sponsor **IN BRIEF:** - ๐Ÿ‡บ๐Ÿ‡ธ [PGConf NYC](https://2025.pgconf.nyc/) is taking place this September 29-October 1. [The schedule has been published](https://postgresql.us/events/pgconfus2025/schedule/) and it's packed with great talks. - ๐Ÿ‡ฌ๐Ÿ‡ง [PGDay UK](https://2025.pgday.uk/) is back, taking place in London this September 9. [Here's the schedule so far.](https://pgday.uk/events/pgdayuk2025/schedule/) - The organizers of PGDay Lowlands want to [encourage you to test out PostgreSQL 18 Beta 2](https://2025.pgday.nl/testing-pg/) by putting your name on a 'wall of testers' and entering you into a raffle for a PGDay Lowlands ticket. - PlanetScale explains [โ–ถ๏ธ how they're bringing _PlanetScale Insights_](https://bsky.app/profile/planetscale.com/post/3lvo7vbfwys22), a popular feature from their MySQL platform, to their new Postgres offering too. - ๐Ÿ‡ซ๐Ÿ‡ฎ [Nordic PGDay 2026](https://2026.nordicpgday.org/) is taking place next year in Helsinki, Finland on March 24. The CFP doesn't open until September, but if you're interested in being on the program committee, [they're looking for volunteers.](https://2026.nordicpgday.org/cfp/) - Fujitsu's [Shlok Kumar Kyal](https://postgresql.life/post/shlok_kumar_kyal/) is this week's _PostgreSQL Person of the Week_interviewee. [No, You Don't _Necessarily_ Need Extensions to Compact Postgres Tables](https://kmoppel.github.io/2025-08-06-no-you-dont-need-extensions-to-compact-postgres-tables/) โ€” Letโ€™s say you canโ€™t use [pg_squeeze](https://github.com/cybertec-postgresql/pg_squeeze) or [pg_repack](https://github.com/reorg/pg_repack) on your server, what can you do to reduce bloat in a large table without a full vacuum? Kaarel offers an approach. Kaarel Moppel [High Availability and Postgres Full-Sync Replication](https://multigres.com/blog/postgres-ha-full-sync) โ€” [Multigres](https://multigres.com/) is a project to build an adaptation of Vitess for Postgres for multi-tenant, highly available scaling. In this post the creator of both Multigres and Vitess explains the issues involved and how they plan to tackle them. Sugu Sougoumarane ๐Ÿ“„ [Debugging Postgres Errors with Stack Traces](https://www.enterprisedb.com/blog/stack-traces-postgres-errors-backtracefunctions) โ€“ A neat technique. Phil Eaton ๐Ÿ“„ [When Postgres Performance Slows Down, Here's Where to Look First](https://stormatics.tech/blogs/when-postgresql-performance-slows-down-here-is-where-to-look-first) Umair Shahid (Stormatics) ๐Ÿ“„ [A Quick Book Review of _Mastering PostgreSQL 17_](https://stokerpostgresql.blogspot.com/2025/08/book-review-mastering-postgresql-17.html) Dave Stokes ๐Ÿ“„ [Do You Know the `LATERAL JOIN` in SQL?](https://mayallo.com/lateral-join/) Mohamed Mayallo **RELEASES:** [pg_squeeze 1.9: Extension to Automate Table Bloat Cleanup](https://github.com/cybertec-postgresql/pg_squeeze) โ€” While not a replacement for vacuuming, this extension goes a step further to gain even more space improvements in-situ and now supports Postgres 18. CYBERTEC [plpgsql_check 2.8.2: A PL/pgSQL Code Checker](https://github.com/okbob/plpgsql_check) โ€” A specialized tool for when you want to find any errors lurking in your PL/pgSQL functions. Pavel Stehule - [Pigsty 3.6](https://www.postgresql.org/about/news/pigsty-36-the-meta-distribution-for-postgresql-3111/) โ€“ A popular 'meta-distribution' of Postgres, now all ready for Postgres 18. - [pgrx 0.16](https://github.com/pgcentralfoundation/pgrx/releases/tag/v0.16.0) โ€“ A way to build Postgres extensions with Rust and now with support for Postgres 18 beta 2. - [PeerDB 0.31](https://github.com/PeerDB-io/peerdb) โ€“ Stream data from Postgres to data warehouses, queues and storage engines. - [tbls 1.87](https://github.com/k1LoW/tbls) โ€“ Auto document a database in Markdown format, such as in CI. - [ChartDB 1.14](https://github.com/chartdb/chartdb) โ€“ Open-source diagram-based database editor. - [Martin 0.18](https://github.com/maplibre/martin/releases/tag/v0.18.0) โ€“ Fast Rust-powered PostGIS map tile server. **AND A BONUS READ:** [How Instacart Built a Modern Search Infrastructure on Postgres](https://tech.instacart.com/how-instacart-built-a-modern-search-infrastructure-on-postgres-c528fa601d54) โ€” Somehow we missed it when it was posted back in May, but this is a neat look at how a popular grocery delivery/pickup service shifted its full text search approach from Elasticsearch to Postgres while introducing semantic and hybrid search elements. Ankit Mittal et al. (Instacart) _We're now off for a week so will be back on Thursday, August 21._ **Got a new email?** You can [change your address here](https://postgresweekly.com/edit_subscription/*|UID|*). --- **Bored of us?** [Click here to stop getting Postgres Weekly](https://postgresweekly.com/leave/*|UID|*). --- **Got a link for us?** Reply and tell us. We can't include everything but we'll look at anything you send. _Thanks!_ --- Published by Cooper Press Ltd. Fairfield Enterprise Centre, Louth, LN11 0LS, United Kingdom Postgres, PostgreSQL and the Slonik Logo are trademarks or registered trademarks of the PostgreSQL Community Association of Canada. [Stop getting this newsletter](https://postgresweekly.com/leave/*|UID|*).