.tip

Mar 22, 2026 · one of the small things

Turn on pg_stat_statements before you need it

The first question in every database incident is "which query", and pg_stat_statements is the only thing that can answer it from history, not just from the moment you happened to look.

SELECT calls, mean_exec_time, query
FROM pg_stat_statements ORDER BY total_exec_time DESC LIMIT 10;

It costs a few percent. An afternoon spent without it costs more.

postgresqlobservability

~/tips/today — 2026-10-19

~cat tips/today

Never build an index on a live table without CONCURRENTLY

postgresqlmigrations

A plain CREATE INDEX takes a lock that blocks every write to the table for the whole build. On a big table that means minutes of outage that look like a hung app.

CREATE INDEX CONCURRENTLY orders_customer_idx ON orders (customer_id);

It's slower and can't run inside a transaction, so you'll have to tell your migration tool. If it fails halfway, it leaves an invalid index behind, so check pg_index.indisvalid and drop it before you retry.

↵ open y yesterday l ls /tips

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