2 files changed, 31 insertions, 0 deletions
diff --git a/db/migrate/20180710162338_add_foreign_key_from_notification_settings_to_users.rb b/db/migrate/20180710162338_add_foreign_key_from_notification_settings_to_users.rb
new file mode 100644
index 00000000000..91656f194e5
--- /dev/null
+++ b/db/migrate/20180710162338_add_foreign_key_from_notification_settings_to_users.rb
@@ -0,0 +1,30 @@
+class AddForeignKeyFromNotificationSettingsToUsers < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  class NotificationSetting < ActiveRecord::Base
+    self.table_name = 'notification_settings'
+
+    include EachBatch
+  end
+
+  class User < ActiveRecord::Base
+    self.table_name = 'users'
+  end
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    NotificationSetting.each_batch(of: 1000) do |batch|
+      batch.where('NOT EXISTS (?)', User.select(1).where('users.id = notification_settings.user_id'))
+        .delete_all
+    end
+
+    add_concurrent_foreign_key(:notification_settings, :users, column: :user_id, on_delete: :cascade)
+  end
+
+  def down
+    remove_foreign_key(:notification_settings, column: :user_id)
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 769baa825a5..2bef2971f29 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -2350,6 +2350,7 @@ ActiveRecord::Schema.define(version: 20180726172057) do
   add_foreign_key "milestones", "projects", name: "fk_9bd0a0c791", on_delete: :cascade
   add_foreign_key "note_diff_files", "notes", column: "diff_note_id", on_delete: :cascade
   add_foreign_key "notes", "projects", name: "fk_99e097b079", on_delete: :cascade
+  add_foreign_key "notification_settings", "users", name: "fk_0c95e91db7", on_delete: :cascade
   add_foreign_key "oauth_openid_requests", "oauth_access_grants", column: "access_grant_id", name: "fk_oauth_openid_requests_oauth_access_grants_access_grant_id"
   add_foreign_key "pages_domains", "projects", name: "fk_ea2f6dfc6f", on_delete: :cascade
   add_foreign_key "personal_access_tokens", "users"