Migration Squashing
Migration squashing
Version history
- Introduced in GitLab 16.3.
Migration squashing combines multiple database migrations into a single schema definition to improve database setup performance and maintain a manageable migration history.
When to use migration squashing
Use migration squashing at the following times:
- At the start of each major release cycle
- After a required stop
- When the number of migrations has grown significantly (typically more than 200 migrations)
Squash migrations
To squash migrations from a previous version (such as 16.10), run:
bundle exec rake "gitlab:db:squash[origin/16-10-stable-ee]"This Rake task:
- Removes all migrations from the previous version
- Updates the schema version references in relevant files
- Cleans up finalized batched background migrations
- Updates CI configuration for database rollbacks
Parameters
| Parameter | Description |
|---|---|
[origin/16-10-stable-ee] |
The Git reference to use as a baseline for migration squashing. This should be the stable branch of the previous version. |
Troubleshooting
Missing schema references
If you encounter errors related to missing schema references, check:
- Migration spec files that might reference old migrations
- Background migration files that might need manual updates
- Documentation that references specific migration versions