Apply every schema change through ordered, reviewed migration files in version control.
Ad hoc manual DDL drifts environments apart and makes changes impossible to review, replay, or roll back.
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Hand-running ALTER statements in each environment causes schema drift: prod and staging silently diverge, and there is no record of what changed or how to undo it. Versioned migrations make schema a reviewable, replayable, ordered artifact.
-- Bad: someone runs this by hand in prod only
psql -c "ALTER TABLE users ADD COLUMN phone text;"-- Good: ordered migration file, committed and applied everywhere
migrations/20260601_add_users_phone.sql
ALTER TABLE users ADD COLUMN phone text;