Git for Database Work Basics

# Daily migration work
git checkout main && git pull --ff-only
git checkout -b feat/DB-128-add-orders-priority
# edit db/migrations/V20260709_128__orders_priority.sql
git add db/migrations/
git commit -m "feat(db): add orders.priority column [DB-128]"
git push -u origin feat/DB-128-add-orders-priority
# Open PR with EXPLAIN + rollback sections filled

db/
├── migrations/
│   ├── V20260701_100__baseline.sql
│   ├── V20260709_128__orders_priority.sql
│   └── R__views.sql              # repeatable (Flyway)
├── rollback/
│   └── V20260709_128__orders_priority_down.sql
└── seeds/
    └── dev_fixtures.sql

-- V20260709_128__orders_priority.sql
-- Ticket: DB-128
-- Lock risk: medium (CONCURRENTLY index in separate file)
-- Deploy: before orders-api v2.7.0
ALTER TABLE orders ADD COLUMN IF NOT EXISTS priority text NOT NULL DEFAULT 'normal';

-- V20260709_129__orders_priority_index.sql
-- executeInTransaction=false (Flyway)
CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_orders_priority ON orders (priority);

## Database PR
- [ ] Staging flyway migrate applied
- [ ] Lock watch query run during migration
- [ ] Rollback SQL linked
- [ ] App deploy order documented (migration before code)
- [ ] EXPLAIN attached if query/index change

# .github/workflows/db-migrate-staging.yml
- run: flyway -url="${{ secrets.STAGING_JDBC }}" migrate
- run: psql "$STAGING_URL" -c "SELECT version, success FROM flyway_schema_history ORDER BY installed_rank DESC LIMIT 3;"

Correct:  migration merge → staging migrate → prod migrate → app deploy
Wrong:    app deploy first → code expects missing column

SELECT installed_rank, version, description, success
FROM flyway_schema_history ORDER BY installed_rank DESC LIMIT 5;