removal_date:"2022-05-22"# the date of the milestone release when this feature is planned to be removed
breaking_change:true
body:|
The syntax of [GitLab's database](https://docs.gitlab.com/omnibus/settings/database.html)
configuration located in `database.yml` has changed and the legacy format has been removed.
The legacy format supported a single PostgreSQL adapter, whereas the new format supports multiple databases.
The `main:` database needs to be defined as a first configuration item.
This change only impacts users compiling GitLab from source, all the other installation methods handle this configuration automatically.
Instructions are available [in the source update documentation](https://docs.gitlab.com/ee/update/upgrading_from_source.html#new-configuration-options-for-databaseyml).
