Mysql

# MySQL Skill

> The world's most popular open source database.

## Ecosystem Graph Preview

```mermaid
graph LR
  mysql["mysql"]:::core
  classDef core fill:#f9f,stroke:#333,stroke-width:4px;
  drizzle -- "integrates with" --> mysql
  mysql -- "extended by" --> planetscale
  mysql -- "integrates with" --> prisma
  mysql -- "alternative to" --> postgresql
  postgresql -- "alternative to" --> mysql
  prisma -- "integrates with" --> mysql
```

## Recommended Next Skills

- **[postgresql](/skills/postgresql)** (Score: 0.93)
  *Why: Direct relationship, Both are Databases, Shared ecosystem (database), Can deploy to aws, Similar network profile*
- **[prisma](/skills/prisma)** (Score: 0.73)
  *Why: Direct relationship, Both are Databases, Similar network profile*
- **[drizzle](/skills/drizzle)** (Score: 0.72)
  *Why: Direct relationship, Both are Databases, Similar network profile*

## Quick Start
MySQL is highly optimized for read-heavy web workloads. The InnoDB storage engine provides robust ACID compliance.

```bash
docker run -d -p 3306:3306 -e MYSQL_ROOT_PASSWORD=secret mysql:8
```

## Production Patterns
### Index Optimizations
MySQL heavily relies on clustered indexes (the Primary Key). Always define an auto-incrementing integer or sequential UUID (UUID v7) as your primary key to prevent massive index fragmentation and page splits during high-volume inserts.

## Architecture & Scaling
### Replication
MySQL's asynchronous replication is the standard for scaling read traffic. Write to the Primary node, and read from Read Replicas, but ensure your application can handle the replication lag (milliseconds).

## Error Recovery
Use `EXPLAIN` to diagnose slow queries. If MySQL is performing a 'filesort' or full table scan, you are missing a critical composite index.

## Security Notes
Disable `local_infile` to prevent arbitrary file reading vulnerabilities. Ensure `sql_mode` includes `STRICT_ALL_TABLES` to prevent MySQL from silently truncating strings that exceed column lengths.

## References
- [MySQL Docs](https://dev.mysql.com/doc/)

## Why use this skill
Use this when your agent works with **mysql** — structured patterns beat pasted docs and prevent common hallucinations.

## AI pitfalls
- Inventing column names or schema fields
- Using deprecated driver methods or wrong connection strings
- Omitting connection pooling or transaction boundaries

## Production checklist
- [ ] Migrations version-controlled and applied via CI
- [ ] Connection limits and pooling configured
- [ ] Backups and restore procedure documented

## Related skills
- [`planetscale`](../planetscale/SKILL.md) — extended by
- [`prisma`](../prisma/SKILL.md) — integrates with
- [`postgresql`](../postgresql/SKILL.md) — alternative to

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> **Last Verified:** 2026-07-02