diachron/docs/migrations-and-seeders-and-database-table-ownership.md

Some database tables are owned by diachron and some are owned by the application.

This also applies to seeders: some are owned by diachron and some by the application.

The database's structure is managed by migrations written in SQL.

Each migration gets its own file. These files' names should match yyyy-mm-dd_ss-description.sql, eg 2026-01-01_01-users.sql.

Files are sorted lexicographically by name and applied in order.

Note: in the future we may relax or modify the restriction on migration file names, but they'll continue to be applied in lexicographical order.

framework and application migrations

Migrations owned by the framework are kept in a separate directory from those owned by applications. Pending framework migrations, if any, are applied before pending application migrations, if any.

diachron will go to some lengths to ensure that framework migrations do not break applications.

no downward migrations

diachron does not provide them. "The only way out is through."

When developing locally, you can use the command develop reset-db. NEVER USE THIS IN PRODUCTION! Always be sure that you can "get back to where you were". Being careful when creating migrations and seeders can help, but dumping and restoring known-good copies of the database can also take you a long way.