DB Migration Safety Checker

The migration ran instantly in staging and locked a 40-million-row table in production for nine minutes — because staging had 400 rows. This skill audits your migration before it touches production: lock acquisition analysis, estimated execution time at your actual data volume, index build strategy (concurrent vs. blocking), column default pitfalls, constraint validation timing, and the exact zero-downtime sequence if your migration needs one. It also writes the rollback script, because migrations that can't be undone shouldn't be run without one. Use it on every migration that touches a table with more than 10,000 rows, adds a NOT NULL column, drops anything, or runs during business hours. Give it your migration file and your production table sizes; it returns the risk assessment and the safe execution plan.