Migrate issuable states to integer patch 1

Patch 1 that migrates issues/merge requests states from integer to string.
On this commit we are only adding the state_id column and syncing it with a backgroud migration.

On Patch 2 the code to use the new integer column will be deployed and the old column will be
removed.

1 files changed, 29 insertions, 0 deletions

diff --git a/lib/gitlab/background_migration/sync_issuables_state_id.rb b/lib/gitlab/background_migration/sync_issuables_state_id.rb
new file mode 100644
index 00000000000..1ac86b8acf2
--- /dev/null
+++ b/lib/gitlab/background_migration/sync_issuables_state_id.rb
@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+# rubocop:disable Style/Documentation
+
+module Gitlab
+  module BackgroundMigration
+    class SyncIssuablesStateId
+      def perform(start_id, end_id, model_class)
+        populate_new_state_id(start_id, end_id, model_class)
+      end
+
+      def populate_new_state_id(start_id, end_id, model_class)
+        Rails.logger.info("#{model_class.model_name.human} - Populating state_id: #{start_id} - #{end_id}")
+
+        ActiveRecord::Base.connection.execute <<~SQL
+          UPDATE #{model_class.table_name}
+          SET state_id =
+            CASE state
+            WHEN 'opened' THEN 1
+            WHEN 'closed' THEN 2
+            WHEN 'merged' THEN 3
+            WHEN 'locked' THEN 4
+            END
+          WHERE state_id IS NULL
+          AND id BETWEEN #{start_id} AND #{end_id}
+        SQL
+      end
+    end
+  end
+end