DBExplore — Postgres engineeringTechnical posts on PostgreSQL internals, query plans, upgrades, replication and fleet observability.https://www.dbexplore.com/enhello@dbexplore.com (Karthik M)The pgvector index nobody measuredhttps://www.dbexplore.com/blog/pgvector-index-outgrew-memory/https://www.dbexplore.com/blog/pgvector-index-outgrew-memory/Vector search in Postgres degrades quietly. The index crosses RAM, the build runs on disk, recall decays with churn, and none of it raises an alert.Wed, 30 Sep 2026 00:00:00 GMTKarthik Mpgvectorvector-searchpostgres-internalsAurora's writer endpoint can lie to youhttps://www.dbexplore.com/blog/aurora-writer-endpoint-can-lie-to-you/https://www.dbexplore.com/blog/aurora-writer-endpoint-can-lie-to-you/CloudWatch measures instances. Your application talks to endpoints. For the minute those disagree, every instance metric looks healthy while writes fail.Wed, 23 Sep 2026 00:00:00 GMTKarthik Maurorahigh-availabilitymonitoringPostgreSQL 18 moved the WAL I/O countershttps://www.dbexplore.com/blog/postgres-18-moved-the-wal-io-counters/https://www.dbexplore.com/blog/postgres-18-moved-the-wal-io-counters/pg_stat_wal lost its write and sync columns to pg_stat_io in 18. Nothing errors. The numbers just stop arriving, and most monitoring never notices.Wed, 16 Sep 2026 00:00:00 GMTKarthik Mpostgres-18postgres-internalsmonitoring75% of our query-plan storage was duplicatehttps://www.dbexplore.com/blog/75-percent-of-our-plan-storage-was-duplicate/https://www.dbexplore.com/blog/75-percent-of-our-plan-storage-was-duplicate/Thousands of stored plans turned out to be a few hundred distinct shapes. What a structural fingerprint keeps, what it strips, and why regressions depend on it.Thu, 27 Aug 2026 00:00:00 GMTKarthik Mquery-plansplan-regressionpostgres-internals