39 lines
1.7 KiB
Markdown
39 lines
1.7 KiB
Markdown
---
|
|
stage: none
|
|
group: unassigned
|
|
info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
|
|
---
|
|
|
|
# Delete existing migrations
|
|
|
|
When removing existing migrations from the GitLab project, you have to take into account
|
|
the possibility of the migration already been included in past releases or in the current release, and thus already executed on GitLab.com and/or in self-managed instances.
|
|
|
|
Because of it, it's not possible to delete existing migrations, as that could lead to:
|
|
|
|
- Schema inconsistency, as changes introduced into the database were not rolled back properly.
|
|
- Leaving a record on the `schema_versions` table, that points out to migration that no longer exists on the codebase.
|
|
|
|
Instead of deleting we can opt for disabling the migration.
|
|
|
|
## Pre-requisites to disable a migration
|
|
|
|
Migrations can be disabled if:
|
|
|
|
- They caused a timeout or general issue on GitLab.com.
|
|
- They are obsoleted, for example, changes are not necessary due to a feature change.
|
|
- Migration is a data migration only, that is, the migration does not change the database schema.
|
|
|
|
## How to disable a data migration?
|
|
|
|
In order to disable a migration, the following steps apply to all types of migrations:
|
|
|
|
1. Turn the migration into a no-op by removing the code inside `#up`, `#down`
|
|
or `#perform` methods, and adding `# no-op` comment instead.
|
|
1. Add a comment explaining why the code is gone.
|
|
|
|
Disabling migrations requires explicit approval of Database Maintainer.
|
|
|
|
## Examples
|
|
|
|
- [Disable scheduling of productivity analytics](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/17253)
|