mysql

# MySQL Use this skill to make safe, measurable MySQL/InnoDB changes. ## Workflow 1. Define workload and constraints (read/write mix, latency target, data volume, MySQL version, hosting platform). 2. Read only the relevant reference files linked in each section below. 3. Propose the smallest change that can solve the problem, including trade-offs. 4. Validate with evidence (`EXPLAIN`, `EXPLAIN ANALYZE`, lock/connection metrics, and production-safe rollout steps). 5. For production changes, include rollback and post-deploy verification. ## Schema Design - Prefer narrow, monotonic PKs (`BIGINT UNSIGNED AUTO_INCREMENT`) for write-heavy OLTP tables. - Avoid random UUID values as clustered PKs; if external IDs are required, keep UUID in a secondary unique column. - Always `utf8mb4` / `utf8mb4_0900_ai_ci`. Prefer `NOT NULL`, `DATETIME` over `TIMESTAMP`. - Lookup tables over `ENUM`. Normalize to 3NF; denormalize only for measured hot paths. References: - [primary-keys](https://raw.githubusercontent.com/planetscale/database-skills/main/skills/mysql/references/primary-keys.md) - [data-types](https://raw.githubusercontent.com/planetscale/database-skills/main/skills/mysql/references/data-types.md) - [character-sets](https://raw.githubusercontent.com/planetscale/database-skills/main/skills/mysql/references/character-sets.md) - [json-column-patterns](https://raw.githubusercontent.com/planetscale/database-skills/main/skills/mysql/references/json-column-patterns.md) ## Indexing - Compo...