Add migration to remove orphaned notification settings

1 files changed, 24 insertions, 0 deletions

diff --git a/db/migrate/20170418103908_delete_orphan_notification_settings.rb b/db/migrate/20170418103908_delete_orphan_notification_settings.rb
new file mode 100644
index 00000000000..e4b9cf65936
--- /dev/null
+++ b/db/migrate/20170418103908_delete_orphan_notification_settings.rb
@@ -0,0 +1,24 @@
+class DeleteOrphanNotificationSettings < ActiveRecord::Migration
+  DOWNTIME = false
+
+  def up
+    execute("DELETE FROM notification_settings WHERE EXISTS (SELECT true FROM (#{orphan_notification_settings}) AS ns WHERE ns.id = notification_settings.id)")
+  end
+
+  def down
+    # This is a no-op method to make the migration reversible.
+    # If someone is trying to rollback for other reasons, we should not throw an Exception.
+    # raise ActiveRecord::IrreversibleMigration
+  end
+
+  def orphan_notification_settings
+    <<-SQL
+      SELECT notification_settings.id
+      FROM   notification_settings
+             LEFT OUTER JOIN namespaces
+                          ON namespaces.id = notification_settings.source_id
+      WHERE  notification_settings.source_type = 'Namespace'
+             AND namespaces.id IS NULL
+    SQL
+  end
+end