Add cleanup migration for MR's mutliple assigneesid-clean-up-mr-assignees-migration

The migration steals the remaining background jobs
of populating MRs with assignees, executes them
synchronously and then makes sure that all the
assignees are migrated

4 files changed, 53 insertions, 6 deletions

diff --git a/changelogs/unreleased/id-clean-up-mr-assignees.yml b/changelogs/unreleased/id-clean-up-mr-assignees.yml
new file mode 100644
index 00000000000..7ff03c9f00b
--- /dev/null
+++ b/changelogs/unreleased/id-clean-up-mr-assignees.yml
@@ -0,0 +1,5 @@
+---
+title: Add cleanup migration for MR's multiple assignees
+merge_request: 30261
+author:
+type: changed
diff --git a/db/post_migrate/20190702173936_populate_remaining_merge_request_assignees.rb b/db/post_migrate/20190702173936_populate_remaining_merge_request_assignees.rb
new file mode 100644
index 00000000000..c435b94015d
--- /dev/null
+++ b/db/post_migrate/20190702173936_populate_remaining_merge_request_assignees.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class PopulateRemainingMergeRequestAssignees < ActiveRecord::Migration[5.1]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+  BATCH_SIZE = 10_000
+  MIGRATION = 'PopulateMergeRequestAssigneesTable'
+
+  disable_ddl_transaction!
+
+  def up
+    Gitlab::BackgroundMigration.steal(MIGRATION)
+
+    Gitlab::BackgroundMigration::PopulateMergeRequestAssigneesTable.new.perform_all_sync(batch_size: BATCH_SIZE)
+  end
+end
diff --git a/lib/gitlab/background_migration/populate_merge_request_assignees_table.rb b/lib/gitlab/background_migration/populate_merge_request_assignees_table.rb
index a4c6540c61b..eb4bc0aaf28 100644
--- a/lib/gitlab/background_migration/populate_merge_request_assignees_table.rb
+++ b/lib/gitlab/background_migration/populate_merge_request_assignees_table.rb
@@ -18,6 +18,14 @@ module Gitlab
         execute("INSERT INTO merge_request_assignees (merge_request_id, user_id) #{select_sql}")
       end
 
+      def perform_all_sync(batch_size:)
+        MergeRequest.each_batch(of: batch_size) do |batch|
+          range = batch.pluck('MIN(id)', 'MAX(id)').first
+
+          perform(*range)
+        end
+      end
+
       private
 
       def merge_request_assignees_not_exists_clause
diff --git a/spec/lib/gitlab/background_migration/populate_merge_request_assignees_table_spec.rb b/spec/lib/gitlab/background_migration/populate_merge_request_assignees_table_spec.rb
index 4a81a37d341..ad4fa4fe03a 100644
--- a/spec/lib/gitlab/background_migration/populate_merge_request_assignees_table_spec.rb
+++ b/spec/lib/gitlab/background_migration/populate_merge_request_assignees_table_spec.rb
@@ -27,14 +27,19 @@ describe Gitlab::BackgroundMigration::PopulateMergeRequestAssigneesTable, :migra
     merge_requests.create(params)
   end
 
+  before do
+    create_merge_request(2, assignee_id: user.id)
+    create_merge_request(3, assignee_id: user_2.id)
+    create_merge_request(4, assignee_id: user_3.id)
+
+    # Test filtering MRs without assignees
+    create_merge_request(5, assignee_id: nil)
+    # Test filtering already migrated row
+    merge_request_assignees.create!(merge_request_id: 2, user_id: user_3.id)
+  end
+
   describe '#perform' do
     it 'creates merge_request_assignees rows according to merge_requests' do
-      create_merge_request(2, assignee_id: user.id)
-      create_merge_request(3, assignee_id: user_2.id)
-      create_merge_request(4, assignee_id: user_3.id)
-      # Test filtering already migrated row
-      merge_request_assignees.create!(merge_request_id: 2, user_id: user_3.id)
-
       subject.perform(1, 4)
 
       rows = merge_request_assignees.order(:id).map { |row| row.attributes.slice('merge_request_id', 'user_id') }
@@ -53,4 +58,13 @@ describe Gitlab::BackgroundMigration::PopulateMergeRequestAssigneesTable, :migra
       end
     end
   end
+
+  describe '#perform_all_sync' do
+    it 'executes peform for all merge requests in batches' do
+      expect(subject).to receive(:perform).with(2, 4).ordered
+      expect(subject).to receive(:perform).with(5, 5).ordered
+
+      subject.perform_all_sync(batch_size: 3)
+    end
+  end
 end