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    DB Migration Safety Reviewer

    1

    Review schema migrations for lock risk, data loss, backfill cost, and rolling-deploy breakage — get a verdict, safe rewrite, and deploy sequence.

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    DB Migration Safety Reviewer

    DB Migration Safety Reviewer

    Example session with this skill installed

    Database: PostgreSQL 15
    Table size: not provided (production; estimate unknown)
    Deployment: rolling deploy (no maintenance window)
    Context: billing service; subscriptions table is hot path

    Migration SQL

    -- migration_2026_03_12_subscriptions.sql

    ALTER TABLE subscriptions
    ADD COLUMN plan_tier TEXT NOT NULL;

    CREATE INDEX idx_subscriptions_account_id

      ON subscriptions(account_id);

UPDATE subscriptions
SET trial_ends_at = created_at + INTERVAL '14 days'
WHERE trial_ends_at IS NULL;

    ALTER TABLE subscriptions
    DROP COLUMN old_price_cents;

    • Read your context and instructions
    • Compiled the db migration safety

    DB Migration Safety Review

    1. Risk Summary

    | Database | PostgreSQL 15 |
    | Statements reviewed | 4 |
    | Migration Risk Verdict | BLOCK |
    | Risk Score | 0 / 100 |
    | Critical / High / Medium / Low | 1 / 3 / 0 / 0 |
    | Table size assumption | large (not provided) |

    3. Risk Findings

    MIG-01 CRITICAL lock — ADD plan_tier NOT NULL without DEFAULT
    → Add nullable/DEFAULT, backfill, then SET NOT NULL
    MIG-02 HIGH lock — CREATE INDEX blocks writes
    → CREATE INDEX CONCURRENTLY + verify valid
    MIG-03 HIGH backfill — Unbatched UPDATE on hot table
    → Batch 1k–10k with statement_timeout
    MIG-04 HIGH data-loss — DROP old_price_cents irreversible
    → Stop reading in code first; drop later

    6. Deploy Sequence

    Expand → Migrate → Contract (destructive last)

    JSON: verdict "BLOCK", risk_score 0
    Disclaimer: Review aid; not a substitute for staging tests, backups, or DBA review.

    Connects securely to your tools. The creator never sees your data.

    What you get

    Prevent production downtime by catching long-running table locks before deploy.Ensure zero-downtime schema changes during rolling application deployments.Generate step-by-step safe execution plans for complex data backfills.Verify rollback feasibility and identify destructive operations lacking a path back.Pre-prod review before running a migration in CI/CDCheck whether CREATE INDEX / ALTER TABLE will lock a hot tablePlan safe backfills instead of one giant UPDATERolling-deploy expand → migrate → contract for breaking schema changesCatch ADD COLUMN NOT NULL without default before it fails in productionSecond pair of eyes for destructive drops / type changes

    About this skill

    The problem

    Schema migrations are the quietest way to cause an outage: table locks, failed NOT NULL adds, irreversible drops, and rolling-deploy breaks when old pods still read a column you just removed. Generic “review this SQL” prompts miss database-specific lock behavior and rarely hand you a safe rewrite.

    What it does

    DB Migration Safety Reviewer is a production-safety review for DDL/DML migrations. It returns:

    • A Migration Risk Verdict: SAFE-TO-SHIP / SHIP-WITH-CAUTION / BLOCK
    • A deterministic Risk Score (0–100)
    • Severity-ranked findings across lock, data-loss, backfill, compatibility, and rollback
    • A safe-execution rewrite for every risky statement (e.g. CONCURRENTLY, batched backfill, expand-migrate-contract)
    • Rollback plan + rolling-deploy sequence
    • Pre-flight checklist + Migration Review JSON for CI/docs

    Frameworks & tools

    • PostgreSQL, MySQL, and SQLite behavior differences
    • Five-dimension risk model + hard verdict gates
    • Common patterns: indexes, type changes, NOT NULL, FK validation, drops, large UPDATEs
    • Works from pasted SQL or migration files in your agent

    Why this beats prompting it yourself

    • Database-aware rules (e.g. Postgres CONCURRENTLY vs MySQL online DDL tools)
    • Hard gates so CRITICAL issues force BLOCK — not a soft “maybe fine”
    • Safe rewrites, not only warnings
    • Rolling-deploy compatibility built into the plan
    • Assumes large tables when size is unknown (worst case) and labels assumptions
    • Read-only: never executes against your database

    Use cases

    • Backend engineers shipping migrations under rolling deploys
    • DBAs reviewing lock and data-loss risk before a release
    • Teams adding indexes without a maintenance window
    • Destructive or backfill-heavy changes that need a staged plan

    Known limitations

    • Cannot measure real lock duration or row counts without that input
    • Version-sensitive advice is sharper when you state the DB version
    • Not a substitute for staging tests, backups, or DBA review on high-risk production changes
    • Does not connect to or execute against any database

    How to install

    Works the same in every agent - Claude, Cursor, Codex, Copilot and 20+ more.

    ~30 seconds
    1. 1

      Download the ZIP

      Free skills download straight away. Paid skills unlock right after purchase.

    2. 2

      Unzip into your skills folder

      Every agent reads skills from one folder on your machine. Drop the unzipped folder in there.

    3. 3

      Ask your agent to use it

      Restart the agent if it was already running. It picks the skill up automatically - no config needed.

    Skills folder by agent

    Click the path to copy it. Create the folder if it does not exist yet.

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    Security scanned

    Verified clean 1 month ago

    • Passed all security checks, Safe to install

    Listed1 month ago

    What's inside

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