Merge branch 'id-clean-up-mr-assignees-migration' into 'master'

Add cleanup migration for MR's multiple assignees

See merge request gitlab-org/gitlab-ce!30269

changelogs/unreleased/id-clean-up-mr-assignees.yml

+---
+title: Add cleanup migration for MR's multiple assignees
+merge_request: 30261
+author:
+type: changed

db/post_migrate/20190702173936_populate_remaining_merge_request_assignees.rb

+# 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

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

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
 
-  describe '#perform' do
-    it 'creates merge_request_assignees rows according to merge_requests' do
+  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
       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