cloudthinker-ai Database Migration Review Skill
Review database migration in PR #{{ pr_number }} in {{ repository }} for {{ database_engine }}.
Workflow
Phase 1 — Migration Safety
SAFETY CHECK
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[ ] Locking analysis:
[ ] ALTER TABLE operations assessed for lock duration
[ ] Large table migrations use online DDL or batching
[ ] No exclusive locks on high-traffic tables during peak
[ ] Lock timeout configured
[ ] Backward compatibility:
[ ] Migration is backward-compatible with current code
[ ] Column renames use add-copy-drop pattern
[ ] Column type changes are safe (no data truncation)
[ ] NOT NULL additions have default values
[ ] New columns are nullable or have defaults
[ ] Data integrity:
[ ] Foreign key constraints validated
[ ] CHECK constraints tested with existing data
[ ] UNIQUE constraints verified against current data
[ ] No orphaned records after migration
Phase 2 — Rollback Plan
ROLLBACK ASSESSMENT
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[ ] Down migration provided: YES / NO
[ ] Down migration tested: YES / NO
[ ] Rollback is data-safe (no data loss on rollback): YES / NO
[ ] Rollback time estimate: ___
[ ] Point-of-no-return identified: YES / NO
[ ] If irreversible, backup strategy documented: YES / NO
[ ] Rollback steps documented for on-call: YES / NO
Phase 3 — Performance Impact
PERFORMANCE IMPACT
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[ ] Index changes:
[ ] New indexes justified by query patterns
[ ] Index creation uses CONCURRENTLY (PostgreSQL)
[ ] Unused indexes identified for removal
[ ] Composite index column order is optimal
[ ] Table size impact:
[ ] Estimated table size after migration: ___
[ ] Migration duration estimate: ___
[ ] Disk space requirements: ___
[ ] Query impact:
[ ] Existing queries tested with new schema
[ ] Query plans reviewed post-migration
[ ] ORM model changes aligned with schema
Phase 4 — Deployment Strategy
DEPLOYMENT PLAN
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[ ] Migration sequence:
1. Deploy migration (schema change)
2. Deploy application code
3. Verify application health
4. Clean up (drop old columns if needed)
[ ] Maintenance window required: YES / NO
[ ] Expected downtime: ___
[ ] Pre-migration checklist:
[ ] Database backup taken
[ ] Migration tested on staging with production-size data
[ ] Monitoring alerts configured
[ ] Communication sent to stakeholders
Counter-Rationalizations
| Shortcut | Counter | Why |
|---|---|---|
| "We can skip some steps for this case" | Adapt the workflow steps, don't skip them | Skipped steps are where incidents and oversights originate |
| "The user seems to already know what to do" | Complete all workflow phases with the user | The workflow catches blind spots that experience alone misses |
| "This is a minor case, full process is overkill" | Scale the process down, don't turn it off | Minor cases become major when unstructured; the process scales, not disappears |
| "I'll fill in the details later" | Complete each section before moving on | Deferred details are forgotten; real-time capture is more accurate |
| "The template output isn't necessary" | Always produce the structured output format | Structured output enables comparison, audit trails, and handoff to other teams |
Output Format
Produce a migration review report with:
- Risk assessment (safe / caution / dangerous)
- Locking impact analysis per operation
- Rollback plan evaluation (reversible / partially / irreversible)
- Deployment recommendations (online / maintenance window / phased)
- Specific concerns with remediation steps