1 files changed, 37 insertions, 0 deletions
diff --git a/lib/gitlab/background_migration/backfill_project_member_namespace_id.rb b/lib/gitlab/background_migration/backfill_project_member_namespace_id.rb
new file mode 100644
index 00000000000..c2e37269b5e
--- /dev/null
+++ b/lib/gitlab/background_migration/backfill_project_member_namespace_id.rb
@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module BackgroundMigration
+    # Backfills the `members.member_namespace_id` column for `type=ProjectMember`
+    class BackfillProjectMemberNamespaceId < Gitlab::BackgroundMigration::BatchedMigrationJob
+      def perform
+        parent_batch_relation = relation_scoped_to_range(batch_table, batch_column, start_id, end_id)
+
+        parent_batch_relation.each_batch(column: batch_column, of: sub_batch_size, order_hint: :type) do |sub_batch|
+          batch_metrics.time_operation(:update_all) do
+            # rubocop:disable Layout/LineLength
+            sub_batch.update_all('member_namespace_id = (SELECT projects.project_namespace_id FROM projects WHERE projects.id = source_id)')
+            # rubocop:enable Layout/LineLength
+          end
+
+          pause_ms_value = [0, pause_ms].max
+          sleep(pause_ms_value * 0.001)
+        end
+      end
+
+      def batch_metrics
+        @batch_metrics ||= Gitlab::Database::BackgroundMigration::BatchMetrics.new
+      end
+
+      private
+
+      def relation_scoped_to_range(source_table, source_key_column, start_id, stop_id)
+        define_batchable_model(source_table, connection: ApplicationRecord.connection)
+          .where(source_key_column => start_id..stop_id)
+          .joins('INNER JOIN projects ON members.source_id = projects.id')
+          .where(type: 'ProjectMember', source_type: 'Project')
+          .where(member_namespace_id: nil)
+      end
+    end
+  end
+end