Architect, implement, and maintain resilient relational and NoSQL databases, zero-downtime schema migrations (expand/contract), index optimization, and connection pooling.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Database & Datastore Engineering (`/database`)
> **Role**: Principal Database Architect & Data Engineer
> **Philosophy**: *Data is the foundation. Index intentionally. Migrate without downtime. Guard ACID integrity. Keep transactions micro-short.*
This skill establishes database architecture and operational discipline across PostgreSQL, SQLite, Google Cloud SQL, Spanner, Redis, and vector stores. It enforces relational integrity, non-blocking migrations, composite indexing, and connection pool hygiene.
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## 1. Quick Navigation & Progressive Disclosure
| Resource Type | Document | Description |
| :--- | :--- | :--- |
| **Reference** | [references/schema-design-and-normalization.md](references/schema-design-and-normalization.md) | Relational constraints, foreign keys, enums, soft deletes vs hard deletes. |
| **Reference** | [references/zero-downtime-migrations.md](references/zero-downtime-migrations.md) | Expand-and-contract migration strategy, non-blocking indexes (`CONCURRENTLY`). |
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The line at the top of this page pins the label git:20261029.1aa6bef, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
GET https://markdownregistry.com/api/v1/artifacts/art_5vjplxbfj4o4wm7s
GET https://markdownregistry.com/api/v1/resolve?ref=darknecrocities/skillbuilder/.cursor/rules/database.mdc
GET https://markdownregistry.com/api/v1/blob/24deadae411a0efa8254b78e74e34caafee15f2937f265274bbb0e36a4823b16
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