PostgreSQL Field Notes

Notes for the problems that show up after launch: bad plans, awkward migrations, index debt, vacuum pressure, replica lag, and the small decisions that make PostgreSQL easier to operate.

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SQL Server MariaDB MySQL pgvector and RAG Indexes Slow Queries Locks and Transactions Backups and Durability Replication and WAL Connections and Pooling CPU, Memory, and I/O Vacuum and Bloat Cloud Providers

January 9, 20265 min read

auto_explain in Postgres: Catching Bad Plans After They Happen

auto_explain is for the slow plan you cannot reproduce later. It captures the execution plan when the bad thing actually happens.

January 8, 20265 min read

pgbench for Load Testing: Useful, Limited, and Often Misinterpreted

pgbench measures Postgres throughput under a synthetic workload. It tells you something useful, but only if you understand what its numbers mean.

January 7, 20266 min read

The Postgres Migration Review Checklist I Use Before Approving Any Schema Change

Production migration review is mostly lock review. The SQL can be correct and still dangerous if it rewrites a table, validates too much, or blocks writes.

January 3, 20267 min read

JSONB Indexing in Postgres: Where It Helps and Where People Get Surprised

JSONB columns are great. JSONB indexing has a steeper learning curve than the docs admit. Here is what works in production.