Individual skill

db-migrations

Use when a schema change must ship without downtime — NOT NULL, rename, type change, or backfilling millions of live rows — for the expand-contract sequence and the lock/batching discipline that keeps each step from freezing prod. NOT lock internals or EXPLAIN (that is `postgresdb`), NOT drizzle-kit mechanics (that is `drizzle-orm`), NOT PITR (that is `backups`).

skills/db-migrations/SKILL.md

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Last checked: Nov 10, 2026

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Repository stars (not skill ratings): 574
Repository last updated: Nov 9, 2026
License: MIT

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agent-skills Repository topic
agentic-ai Repository topic
ai-agents Repository topic
ai-coding Repository topic
claude-code Repository topic
cli Repository topic
cline Repository topic
codex Repository topic
coding-assistant Repository topic
cursor Repository topic
migrations Declared skill tag
zero-downtime Declared skill tag
expand-contract Declared skill tag
schema Declared skill tag
backfill Declared skill tag
ddl Declared skill tag
legal Derived category

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SKILL.mdcore · 13,231 bytes
evals/README.mddoc · 774 bytes
evals/cases.yamlasset · 3,207 bytes
references/backfill-and-batching.mddoc · 4,133 bytes
references/expand-contract-playbook.mddoc · 5,665 bytes
references/tools-and-runners.mddoc · 5,187 bytes
scripts/verify.shruns · 4,740 bytes

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# Database migrations without downtime

A production migration is a **sequence**, not a statement. The moment you treat `ALTER TABLE ... NOT NULL`
as one atomic change, you have already lost: the lock blocks every writer, the deploy that depends on the
new column races the deploy that still reads the old one, and a rollback means a second outage. Your job
is to decompose one risky change into a chain of small steps where **every intermediate state is
independently deployable** — the old app keeps working, the new app keeps working, and you can stop at any
point without an outage.

This skill is engine-neutral. It owns the *choreography* — what order to run things in and how to keep each
DDL from freezing the table — across Postgres, MySQL, and serverless variants, whatever runner you use
(Flyway, Alembic, golang-migrate, drizzle-kit, raw SQL).

## Route elsewhere