Create the FK via `add_concurrent_foreign_key` with the option `validate: false` https://docs.gitlab.com/development/database/foreign_keys/#adding-the-fk-constraint-not-valid --- This issue is for Step One of https://docs.gitlab.com/development/database/foreign_keys/#on-an-existing-column : ``` Adding a FK constraint to an existing column is a multi-milestone process: N.M: Add a NOT VALID FK constraint to the column, it will also ensure there are no inconsistent records created or updated.