Create Migration

Create Database Migration

Create a new database migration file for the OWID MySQL 8 database.

Steps

1. Run yarn createDbMigration db/migration/<NewMigrationName> where <NewMigrationName> is a descriptive name for the migration
2. The generated filename will contain a timestamp prefix, so scan the db/migration/ directory to find the actual path of the new file
3. Report the new file path to the user

Naming Guidelines

Choose a descriptive name for the migration that clearly indicates what schema change is being made (e.g., AddUserEmailIndex, CreateAuditLogTable, RemoveDeprecatedColumns).

Writing the Migration

Read db/readme.md before populating the file. In particular: use past migrations in db/migration/ as reference, and always write a down migration in case the change needs to be reverted.

After Writing the Migration

Follow the checklist in db/migration/CLAUDE.md: recreate any views referencing modified columns, update the DB type definitions in packages/@ourworldindata/types/src/dbTypes/, update the table docs in db/docs/, and tell the user the owid/etl and owid/analytics repositories may need adjusting.