1 files changed, 41 insertions, 0 deletions
diff --git a/lib/gitlab/background_migration/backfill_project_settings.rb b/lib/gitlab/background_migration/backfill_project_settings.rb
new file mode 100644
index 00000000000..7ede8de7bd6
--- /dev/null
+++ b/lib/gitlab/background_migration/backfill_project_settings.rb
@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module BackgroundMigration
+    # Back-fill project settings for projects that do not yet have one.
+    class BackfillProjectSettings
+      include Gitlab::Database::DynamicModelHelpers
+
+      def perform(start_id, end_id, batch_table, batch_column, sub_batch_size, pause_ms)
+        batch_relation = relation_scoped_to_range(batch_table, batch_column, start_id, end_id)
+
+        batch_relation.each_batch(column: batch_column, of: sub_batch_size) do |sub_batch|
+          insert_sql = <<~SQL
+            INSERT INTO project_settings (project_id, created_at, updated_at)
+            #{sub_batch.where(project_settings: { project_id: nil })
+                       .select('projects.id, NOW(), NOW()')
+                       .to_sql}
+            ON CONFLICT (project_id) DO NOTHING
+          SQL
+
+          connection.execute(insert_sql)
+
+          pause_ms = 0 if pause_ms < 0
+          sleep(pause_ms * 0.001)
+        end
+      end
+
+      private
+
+      def connection
+        ApplicationRecord.connection
+      end
+
+      def relation_scoped_to_range(source_table, source_key_column, start_id, stop_id)
+        define_batchable_model(:projects, connection: connection)
+          .where(source_key_column => start_id..stop_id)
+          .joins("LEFT OUTER JOIN project_settings ON project_settings.project_id = projects.id")
+      end
+    end
+  end
+end