Database dumps sometimes reference functions in the `discourse_functions` schema. It's possible that some of these functions have been dropped in a newer version of Discourse. In that case, restoring an older backup will fail with a `ERROR: function discourse_functions.something_something() does not exist` error. The restore functionality contains a workaround for that problem, but it didn't work with functions created in plugin migrations.
This commit adds support for temporarily creating missing `discourse_functions` from plugins. And it adds a simple check if the DB migration file even contains the required `DROPPED_TABLES` or `DROPPED_COLUMNS` constant. We don't need to create an instance of the DB migration class unless one of those constants is used. This makes the restore slightly faster and works around a problem with migrations that execute without `up` or `down` methods (e.g. `BackfillChatChannelAndThreadLastMessageIdsPostMigrate`).
After restoring a backup it takes up to 48 hours for uploads stored on S3 to appear in the S3 inventory. This change prevents alerts about missing uploads by preventing the EnsureS3UploadsExistence job from running in the first 48 hours after a restore. During the restore it deletes the count of missing uploads from the PluginStore, so that an alert isn't triggered by an old number.
The `EXECUTE FUNCTION` syntax for `CREATE TRIGGER` statements was introduced in PostgreSQL 11. We need to replace `EXECUTE FUNCTION` with `EXECUTE PROCEDURE` in order to be able to restore backups created with PG12 on PG10.
Rails calls I18n.translate during initialization and by default translation overrides are used. Database migrations would fail if the system tried to migrate from an old version that didn't have the `translation_overrides` table with all its columns yet.
This makes restoring really old backups work again. Running `DISABLE_TRANSLATION_OVERRIDES=1 rake db:migrate` will allow you to upgrade such an old database as well.
Some specs use psql to test database restores and dropping the table after the test needs to happen outside of rspec because of transactions. The previous attempt lead to some changes to be stored in the test database.
