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Engineering: backend-engineering, frontend-engineering, data-engineering, ml-engineering, platform-engineering, qa-methodology Executive: go-to-market, legal-strategy, operational-design, org-design, product-strategy ml-engineering: added missing training-infrastructure.md reference qa-methodology: added test-data-management, performance-testing, security-testing references All frontmatter converted to agent-skills convention. Source: https://github.com/magnus919/hermes-profiles
25 lines
1.1 KiB
Markdown
25 lines
1.1 KiB
Markdown
# Database Migrations
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## Migration Types
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| Type | Risk | Rollback | Example |
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|------|------|----------|---------|
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| Add column (nullable) | Low | Trivial | `ALTER TABLE ADD COLUMN x TEXT` |
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| Add column (NOT NULL) | Medium | Trivial if default provided | `ALTER TABLE ADD COLUMN x INT NOT NULL DEFAULT 0` |
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| Rename column | High | Requires migration | Two-phase: add new, dual-write, backfill, drop old |
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| Drop column | High | Requires restore | Verify no readers first, soft-delete before hard-drop |
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| Create table | Low | Trivial | `CREATE TABLE` |
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| Drop table | Critical | Requires restore | Verify no readers, triply confirm |
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| Data migration | High | Requires rollback script | Transform values, update references |
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## Migration Checklist
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- [ ] Migration reviewed by another engineer
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- [ ] Rollback script exists and is tested
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- [ ] Downtime window confirmed (if required)
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- [ ] Read replicas considered (replication lag)
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- [ ] Foreign key constraints handled
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- [ ] Indexes created after data load (not before)
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- [ ] Migration tested against copy of production data
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- [ ] Query performance verified post-migration
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