Database

This folder contains the code for interacting with our MySQL database. We store wordpress content, charts, data, and more in MySQL.

There are multiple ways to run and serve the database, depending on your needs.

Migrations

If you need to make changes to the MySQL database structure, these are specified by typeorm migration files.

Running all migrations

Run:

yarn runDbMigrations

This runs automatically in the server deploy script, so you only need to run it manually when:

• You are creating a new migration locally, or
• Someone else has created a migration

The database dumps we provide has all migrations already applied.

Creating a migration

Run:

yarn typeorm migration:create db/migration/MigrationName

And then populate the file with the SQL statements to alter the tables, using past migration files for reference if needed. Then run migrations with yarn runDbMigrations.

Make sure you write a down migration in case there is any chance things can go wrong we'd need to revert it.

You can find examples of older migrations here: https://github.com/owid/owid-grapher/tree/2dd7f0661ba6fe7fdfb1ad2a59b9ef7ed7a2ad9f/db/migration

Reverting a migration

To revert the last migration on your local development server, use yarn revertLastDbMigration. Running that repeatedly will revert additional migrations. This is useful when working with migrations locally – when you make a change to an existing migration, you need to revert and re-run it.

If the migration has been run in production, create a new migration that is a duplicate of the one you want to revert, and then swap the up and down functions.

Also, you can always refresh non-production databases from the database dumps.