• Database background migrations
  • Batched background migrations
    • Check the status of batched background migrations
      • From the GitLab UI
      • From the database
    • Enable or disable advanced features
      • Pause batched background migrations
      • Automatic batch size optimization
      • Parallel execution
    • Resolve failed batched background migrations
      • Fix and retry the migration
      • Finish a failed migration manually
      • Mark a failed migration finished
  • Background migrations
    • Check for pending background migrations
    • Check for failed background migrations
• Check for pending advanced search migrations

Migrations for upgrades

When upgrading GitLab, there are two types of migrations to check:

• Database migrations.
• Advanced search migrations.

Read below for detailed information about the two types of migrations.

Database background migrations

Certain releases may require different migrations to be finished before you update to the newer version. Two kinds of migrations exist. They differ, and you should check that both are complete before upgrading GitLab:

• Batched background migrations were introduced in GitLab 14.0. All migrations in GitLab 15.1 and later use this format exclusively.
• Background migrations that are not batched. Used in GitLab 15.0 and earlier.

To decrease the time required to complete these migrations, increase the number of Sidekiq workers that can process jobs in the background_migration queue.

Batched background migrations

To update database tables in batches, GitLab can use batched background migrations. These migrations are created by GitLab developers and run automatically on upgrade. However, such migrations are limited in scope to help with migrating some integer database columns to bigint. This is needed to prevent integer overflow for some tables.

Batched background migrations are handled by Sidekiq and run in isolation, so an instance can remain operational while the migrations are processed. However, performance might degrade on larger instances that are heavily used while batched background migrations are run. You should Actively monitor the Sidekiq status until all migrations are completed.

Check the status of batched background migrations

You can check the status of batched background migrations in the GitLab UI, or by querying the database directly. Before you upgrade GitLab, all migrations must have a Finished status.

If the migrations are not finished and you try to upgrade GitLab, you might see this error:

Expected batched background migration for the given configuration to be marked
as 'finished', but it is 'active':

If you get this error, review the options for how to complete the batched background migrations needed for the GitLab upgrade.

From the GitLab UI

Prerequisites:

• You must have administrator access to the instance.

To check the status of batched background migrations:

1. On the left sidebar, at the bottom, select Admin.
2. Select Monitoring > Background migrations.
3. Select Queued or Finalizing to see incomplete migrations, and Failed for failed migrations.

From the database

Prerequisites:

• You must have administrator access to the instance.

To query the database directly for the status of batched background migrations:

1. Sign in to a psql prompt, according to the directions for your instance’s installation method. For example, sudo gitlab-psql for Linux package installations.

2. To see details on incomplete batched background migrations, run this query in the psql session:

   SELECT
     job_class_name,
     table_name,
     column_name,
     job_arguments
   FROM batched_background_migrations
   WHERE status NOT IN(3, 6);
   

Alternatively, you can wrap the query with gitlab-psql -c "<QUERY>" to check the status of batched background migrations:

gitlab-psql -c "SELECT job_class_name, table_name, column_name, job_arguments FROM batched_background_migrations WHERE status NOT IN(3, 6);"

If the query returns zero rows, all batched background migrations are complete.

Enable or disable advanced features

Batched background migrations provide feature flags that enable you to customize migrations or pause them entirely. These feature flags should only be disabled by advanced users who understand the risks of doing so.

Pause batched background migrations

To pause an ongoing batched background migration, disable the batched background migrations feature. Disabling the feature completes the current batch of migrations, then waits to start the next batch until after the feature is enabled again.

Prerequisites:

• You must have administrator access to the instance.

Use the following database queries to see the state of the current batched background migration:

1. Obtain the ID of the running migration:

   SELECT
    id,
    job_class_name,
    table_name,
    column_name,
    job_arguments
   FROM batched_background_migrations
   WHERE status NOT IN(3, 6);
   

2. Run this query, replacing XX with the ID you obtained in the previous step, to see the status of the migration:

   SELECT
    started_at,
    finished_at,
    finished_at - started_at AS duration,
    min_value,
    max_value,
    batch_size,
    sub_batch_size
   FROM batched_background_migration_jobs
   WHERE batched_background_migration_id = XX
   ORDER BY id DESC
   limit 10;
   

3. Run the query multiple times within a few minutes to ensure no new row has been added. If no new row has been added, the migration has been paused.

4. After confirming the migration has paused, restart the migration (using the enable command above) to proceed with the batch when ready. On larger instances, background migrations can take as long as 48 hours to complete each batch.

Automatic batch size optimization

To maximize throughput of batched background migrations (in terms of the number of tuples updated per time unit), batch sizes are automatically adjusted based on how long the previous batches took to complete.

Parallel execution

To speed up the execution of batched background migrations, two migrations are executed at the same time.

GitLab administrators with access to the GitLab Rails console can change the number of batched background migrations executed in parallel:

ApplicationSetting.update_all(database_max_running_batched_background_migrations: 4)

Resolve failed batched background migrations

If a batched background migration fails, fix and retry it. If the migration continues to fail with an error, either:

• Finish the failed migration manually
• Mark the failed migration finished

Fix and retry the migration

All failed batched background migrations must be resolved to upgrade to a newer version of GitLab. If you check the status of batched background migrations, some migrations might display in the Failed tab with a failed status:

To determine why the batched background migration failed, view the failure error logs or view error information in the UI.

Prerequisites:

• You must have administrator access to the instance.

1. On the left sidebar, at the bottom, select Admin.
2. Select Monitoring > Background migrations.
3. Select the Failed tab. This displays a list of failed batched background migrations.
4. Select the failed Migration to see the migration parameters and the jobs that failed.
5. Under Failed jobs, select each ID to see why the job failed.

If you are a GitLab customer, consider opening a Support Request to debug why the batched background migrations failed.

To correct the problem, you can retry the failed migration.

Prerequisites:

• You must have administrator access to the instance.

1. On the left sidebar, at the bottom, select Admin.
2. Select Monitoring > Background migrations.
3. Select the Failed tab. This displays a list of failed batched background migrations.
4. Select a failed batched background migration to retry by clicking on the retry button ().

To monitor the retried batched background migrations, you can check the status of batched background migrations on a regular interval.

Finish a failed migration manually

To manually finish a batched background migration that failed with an error, use the information in the failure error logs or the database:

   sudo gitlab-rake gitlab:background_migrations:finalize[CopyColumnUsingBackgroundMigrationJob,events,id,'[["id"]\, ["id_convert_to_bigint"]]']

Mark a failed migration finished

There can be cases where the background migration fails: when jumping too many version upgrades, or backward-incompatible database schema changes. (For an example, see issue 393216). Failed background migrations prevent further application upgrades.

When the background migration is determined to be “safe” to skip, the migration can be manually marked finished:

# Start the rails console

connection = ApplicationRecord.connection # or Ci::ApplicationRecord.connection, depending on which DB was the migration scheduled

Gitlab::Database::SharedModel.using_connection(connection) do
  migration = Gitlab::Database::BackgroundMigration::BatchedMigration.find_for_configuration(
    Gitlab::Database.gitlab_schemas_for_connection(connection),
    'BackfillUserDetailsFields',
    :users,
    :id,
    []
  )

  # mark all jobs completed
  migration.batched_jobs.update_all(status: Gitlab::Database::BackgroundMigration::BatchedJob.state_machine.states['succeeded'].value)
  migration.update_attribute(:status, Gitlab::Database::BackgroundMigration::BatchedMigration.state_machine.states[:finished].value)
end

Background migrations

Non-batched migrations are superseded by batched background migrations. Non-batched migrations were gradually phased out during GitLab 14, with the last one used in GitLab 15.0.

Check for pending background migrations

To check for pending non-batched background migrations:

sudo gitlab-rails runner -e production 'puts Gitlab::BackgroundMigration.remaining'
sudo gitlab-rails runner -e production 'puts Gitlab::Database::BackgroundMigration::BatchedMigration.queued.count'

cd /home/git/gitlab
sudo -u git -H bundle exec rails runner -e production 'puts Gitlab::BackgroundMigration.remaining'
sudo -u git -H bundle exec rails runner -e production 'puts Gitlab::Database::BackgroundMigration::BatchedMigration.queued.count'

Check for failed background migrations

To check for non-batched background migrations that have failed:

sudo gitlab-rails runner -e production 'puts Gitlab::Database::BackgroundMigration::BatchedMigration.with_status(:failed).count'

sudo gitlab-rails runner -e production 'puts Gitlab::Database::BackgroundMigration::BatchedMigration.failed.count'

cd /home/git/gitlab
sudo -u git -H bundle exec rails runner -e production 'puts Gitlab::Database::BackgroundMigration::BatchedMigration.with_status(:failed).count'

cd /home/git/gitlab
sudo -u git -H bundle exec rails runner -e production 'puts Gitlab::Database::BackgroundMigration::BatchedMigration.failed.count'

Check for pending advanced search migrations

This section is only applicable if you have enabled the Elasticsearch integration. Major releases require all advanced search migrations to be finished from the most recent minor release in your current version before the major version upgrade. You can find pending migrations by running the following command.

sudo gitlab-rake gitlab:elastic:list_pending_migrations

cd /home/git/gitlab
sudo -u git -H bundle exec rake gitlab:elastic:list_pending_migrations