Agent Skills: dbmate Skill

dbmate Skill

This skill provides comprehensive instructions for managing database migrations in this project using dbmate.

Creating Migrations

When creating new migrations, always follow the /migrate-new workflow. The primary tool for creating a migration is:

dbmate --migrations-dir db/migrations/<engine> new "migration_name"

Replace <engine> with sqlite, postgres, or mysql.

Writing Migrations

Migrations are stored in db/migrations/<engine>/ as .sql files. They follow a specific format:

Structure

Each migration file MUST have two sections:

-- migrate:up
-- SQL statements to apply the change

-- migrate:down
-- SQL statements to reverse the change

Transaction Handling

[!IMPORTANT] DO NOT wrap your SQL in BEGIN/COMMIT blocks. dbmate automatically wraps each migration in a transaction. Adding manual transaction blocks will cause errors and may lead to inconsistent database states.

SQL Guidelines

1. Idempotency: Use IF NOT EXISTS or similar where possible to make migrations safer (e.g., CREATE TABLE IF NOT EXISTS ...).
2. Schema Files: NEVER edit files in db/schema/ manually. They are auto-generated.
3. Engine-Specifics: Ensure you tailor the SQL for the specific database engine.
   • PostgreSQL: Use appropriate types (e.g., TEXT, JSONB).
   • MySQL: Use compatible types (e.g., LONGTEXT for JSON-like data).
   • SQLite: Be mindful of limited ALTER TABLE support.

Applying Migrations

For development, use ./dev-scripts/migrate-all.py. This script:

1. Applies migrations for all engines (PostgreSQL, MySQL, SQLite).
2. Updates the schema files in db/schema/.