What problem does it solve? Database schema changes like adding a NOT NULL column or renaming a column can lock large Postgres tables for minutes and break running code. This Skill encodes safe migration discipline so every schema change avoids downtime-inducing DDL patterns. ## Core Features & Use Cases - Two-Phase Migration Pattern: Splits risky DDL into a backwards-compatible migration, a code deploy, a batched backfill, and a constraint-tightening migration. - Banned DDL Detection: Blocks direct NOT NULL adds, RENAME COLUMN, blocking CREATE INDEX, and edits to already-merged migrations, with CONCURRENTLY indexes as the safe alternative. - Mandatory PR Template: Requires locking impact, row counts, backfill strategy, rollback plan, and dev-branch test evidence in every migration PR. - Use Case: When adding a required status column to a 10M-row orders table, the Skill guides you through a nullable column add, a 10k-row batched backfill with progress logging, and a separate migration that sets NOT NULL. ## Quick Start Ask the agent to add a new required column to an existing Postgres table and it will produce a two-phase Drizzle migration with a batched backfill and a complete safety PR template.
