Add index to notification settings

CHANGELOG

@@ -34,6 +34,7 @@ v 8.9.0 (unreleased)
   - Cache project build count in sidebar nav
   - Reduce number of queries needed to render issue labels in the sidebar
   - Improve error handling importing projects
+  - Remove duplicated notification settings
   - Put project Files and Commits tabs under Code tab
 
 v 8.8.4

db/migrate/20160603180330_remove_duplicated_notification_settings.rb

+class RemoveDuplicatedNotificationSettings < ActiveRecord::Migration
+  def up
+    execute <<-SQL
+      DELETE FROM notification_settings WHERE id NOT IN ( SELECT min_id from (SELECT MIN(id) as min_id FROM notification_settings GROUP BY user_id, source_type, source_id) as dups )
+    SQL
+  end
+end

db/migrate/20160603182247_add_index_to_notification_settings.rb

+class AddIndexToNotificationSettings < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  disable_ddl_transaction!
+
+  def change
+    add_concurrent_index :notification_settings, [:user_id, :source_id, :source_type], { unique: true, name: "index_notifications_on_user_id_and_source_id_and_source_type" }
+  end
+end

lib/gitlab/database/migration_helpers.rb

@@ -19,7 +19,11 @@ module Gitlab
         end
 
         if Database.postgresql?
-          args << { algorithm: :concurrently }
+          if args[2].present?
+            args[2].merge!({ algorithm: :concurrently })
+          else
+            args << { algorithm: :concurrently }
+          end
         end
 
         add_index(*args)