Plans and lints production schema changes as expand/contract phases with the exact lock each PostgreSQL or MySQL 8 statement takes, lock_timeout guards, throttled batched backfills, dual-write and read cutover, and a verification plus reversal per phase, written to the Release Dossier. Includes a zero-dependency Postgres DDL linter. Use when someone asks "is this migration safe to run in prod", "add a NOT NULL column to a big table", "rename or retype this column without downtime", "backfill millions of rows", or when release-risk-classifier scores the data shape criterion R1 or higher. Do NOT use for greenfield schema design with no production rows - use database-schema instead; for a quick single-statement lock check outside a release, use migration-safety-checker; for deciding whether to revert after a failure, use rollback-or-roll-forward.
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name: zero-downtime-db-migrations
description: Plans and lints production schema changes as expand/contract phases with the exact lock each PostgreSQL or MySQL 8 statement takes, lock_timeout guards, throttled batched backfills, dual-write and read cutover, and a verification plus reversal per phase, written to the Release Dossier. Includes a zero-dependency Postgres DDL linter. Use when someone asks "is this migration safe to run in prod", "add a NOT NULL column to a big table", "rename or retype this column without downtime", "backfill millions of rows", or when release-risk-classifier scores the data shape criterion R1 or higher. Do NOT use for greenfield schema design with no production rows - use database-schema instead; for a quick single-statement lock check outside a release, use migration-safety-checker; for deciding whether to revert after a failure, use rollback-or-roll-forward.
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