debian-mirror-gitlab/doc/administration/postgresql/multiple_databases.md

---
stage: Data Stores
group: Pods
info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/product/ux/technical-writing/#assignments
---

# Multiple Databases **(FREE SELF)**

> [Introduced](https://gitlab.com/groups/gitlab-org/-/epics/6168) in GitLab 15.7.

WARNING:
This feature is not ready for production use

By default, GitLab uses a single application database, referred to as the `main` database.

To scale GitLab, you can configure GitLab to use multiple application databases.

Due to [known issues](#known-issues), configuring GitLab with multiple databases is in [**Alpha**](../../policy/alpha-beta-support.md#alpha-features).

## Known issues

- Migrating data from the `main` database to the `ci` database is not supported or documented yet.
- Once data is migrated to the `ci` database, you cannot migrate it back.

## Set up multiple databases

Use the following content to set up multiple databases with a new GitLab installation.

There is no documentation for existing GitLab installations yet.

After you have set up multiple databases, GitLab uses a second application database for
[CI/CD features](../../ci/index.md), referred to as the `ci` database. For
example, GitLab reads and writes to the `ci_pipelines` table in the `ci`
database.

WARNING:
You must stop GitLab before setting up multiple databases. This prevents
split-brain situations, where `main` data is written to the `ci` database, and
the other way around.

### Installations from source

1. [Back up GitLab](../../raketasks/backup_restore.md)
   in case of unforeseen issues.

1. Stop GitLab:

   ```shell
   sudo service gitlab stop
   ```

1. Open `config/database.yml`, and add a `ci:` section under
   `production:`. See `config/database.yml.decomposed-postgresql` for possible
   values for this new `ci:` section. Once modified, the `config/database.yml` should
   look like:

   ```yaml
   production:
     main:
       # ...
     ci:
       adapter: postgresql
       encoding: unicode
       database: gitlabhq_production_ci
       # ...
   ```

1. Save the `config/database.yml` file.

1. Create the `gitlabhq_production_ci` database:

   ```shell
   sudo -u postgres psql -d template1 -c "CREATE DATABASE gitlabhq_production OWNER git;"
   sudo -u git -H bundle exec rake db:schema:load:ci
   ```

1. Lock writes for `ci` tables in `main` database, and the other way around:

   ```shell
   sudo -u git -H bundle exec rake gitlab:db:lock_writes
   ```

1. Restart GitLab:

   ```shell
   sudo service gitlab restart
   ```

### Omnibus GitLab installations

1. [Back up GitLab](../../raketasks/backup_restore.md)
   in case of unforeseen issues.

1. Stop GitLab:

   ```shell
   sudo gitlab-ctl stop
   ```

1. Edit `/etc/gitlab/gitlab.rb` and add the following lines:

   ```ruby
   gitlab_rails['databases']['ci']['enable'] = true
   gitlab_rails['databases']['ci']['db_database'] = 'gitlabhq_production_ci'
   ```

1. Save the `/etc/gitlab/gitlab.rb` file.

1. Reconfigure GitLab:

   ```shell
   sudo gitlab-ctl reconfigure
   ```

1. Optional. Reconfiguring GitLab should create the `gitlabhq_production_ci`. If it did not, manually create the `gitlabhq_production_ci`:

   ```shell
   sudo gitlab-ctl start postgresql
   sudo -u gitlab-psql /opt/gitlab/embedded/bin/psql -h /var/opt/gitlab/postgresql -d template1 -c "CREATE DATABASE gitlabhq_production_ci OWNER gitlab;"
   sudo gitlab-rake db:schema:load:ci

1. Lock writes for `ci` tables in `main` database, and the other way around:

   ```shell
   sudo gitlab-ctl start postgresql
   sudo gitlab-rake gitlab:db:lock_writes
   ```

1. Restart GitLab:

   ```shell
   sudo gitlab-ctl restart
   ```

## Further information

For more information on multiple databases, see [issue 6168](https://gitlab.com/groups/gitlab-org/-/epics/6168).

For more information on how multiple databases work in GitLab, see the [development guide for multiple databases](../../development/database/multiple_databases.md).

Since 2022-07-02, GitLab.com has been running with two separate databases. For more information, see this [blog post](https://about.gitlab.com/blog/2022/06/02/splitting-database-into-main-and-ci/).