https://www.pistack.xyz/tags/zero-downtime/ Recent content in Zero-Downtime on Pi Stack Hugo en-us Mon, 26 Oct 2026 00:00:00 +0000 https://www.pistack.xyz/posts/2026-10-26-postgres-zero-downtime-migrations-pgroll-reshape-graphile-migrate/ Mon, 26 Oct 2026 00:00:00 +0000 https://www.pistack.xyz/posts/2026-10-26-postgres-zero-downtime-migrations-pgroll-reshape-graphile-migrate/ <p><code>ALTER TABLE users ADD COLUMN email_verified boolean NOT NULL DEFAULT false;</code> on a table with 40 million rows takes a lock. In Postgres 11+ adding a column with a non-volatile default is metadata-only, so that particular statement is safe — but <code>ALTER COLUMN ... TYPE</code>, adding a constraint, or backfilling a new index will still queue behind every open transaction and block all writes behind it. One long-running analytics query, and your &ldquo;quick migration&rdquo; becomes a five-minute outage.</p>