Zero-Downtime PostgreSQL Migrations: Locks, Expand-Contract and Safe Backfills

Learn how to change a PostgreSQL schema in production without taking the service down: lock_timeout and the lock queue, indexes with CONCURRENTLY, NOT VALID + VALIDATE constraints, the expand-contract pattern for renames and type changes, and batched backfills. With ready-to-use SQL and Python and the mistakes that cause silent outages.

14 minutes read

2026-07-05

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