1 files changed, 58 insertions, 0 deletions
diff --git a/lib/gitlab/background_migration/backfill_namespace_id_for_project_route.rb b/lib/gitlab/background_migration/backfill_namespace_id_for_project_route.rb
new file mode 100644
index 00000000000..1f0d606f001
--- /dev/null
+++ b/lib/gitlab/background_migration/backfill_namespace_id_for_project_route.rb
@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module BackgroundMigration
+    # Backfills the `routes.namespace_id` column, by setting it to project.project_namespace_id
+    class BackfillNamespaceIdForProjectRoute
+      include Gitlab::Database::DynamicModelHelpers
+
+      def perform(start_id, end_id, batch_table, batch_column, sub_batch_size, pause_ms)
+        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) do |sub_batch|
+          cleanup_gin_index('routes')
+
+          batch_metrics.time_operation(:update_all) do
+            ActiveRecord::Base.connection.execute <<~SQL
+              WITH route_and_ns(route_id, project_namespace_id) AS #{::Gitlab::Database::AsWithMaterialized.materialized_if_supported} (
+                #{sub_batch.to_sql}
+              )
+              UPDATE routes
+              SET namespace_id = route_and_ns.project_namespace_id
+              FROM route_and_ns
+              WHERE id = route_and_ns.route_id
+            SQL
+          end
+
+          pause_ms = [0, pause_ms].max
+          sleep(pause_ms * 0.001)
+        end
+      end
+
+      def batch_metrics
+        @batch_metrics ||= Gitlab::Database::BackgroundMigration::BatchMetrics.new
+      end
+
+      private
+
+      def cleanup_gin_index(table_name)
+        sql = "select indexname::text from pg_indexes where tablename = '#{table_name}' and indexdef ilike '%gin%'"
+        index_names = ActiveRecord::Base.connection.select_values(sql)
+
+        index_names.each do |index_name|
+          ActiveRecord::Base.connection.execute("select gin_clean_pending_list('#{index_name}')")
+        end
+      end
+
+      def relation_scoped_to_range(source_table, source_key_column, start_id, stop_id)
+        define_batchable_model(source_table, connection: ActiveRecord::Base.connection)
+          .joins('INNER JOIN projects ON routes.source_id = projects.id')
+          .where(source_key_column => start_id..stop_id)
+          .where(namespace_id: nil)
+          .where(source_type: 'Project')
+          .where.not(projects: { project_namespace_id: nil })
+          .select("routes.id, projects.project_namespace_id")
+      end
+    end
+  end
+end