Refactor CTE part of big query to joins

ee/app/services/ee/ci/register_job_service.rb

@@ -74,8 +74,14 @@ module EE
 
       # rubocop: disable CodeReuse/ActiveRecord
       def all_namespaces
-        namespaces = ::Namespace.reorder(nil).where('namespaces.id = projects.namespace_id')
-        ::Gitlab::ObjectHierarchy.new(namespaces, options: { skip_ordering: true }).roots
+        if traversal_ids_enabled?
+          ::Namespace
+            .where('namespaces.id = project_namespaces.traversal_ids[1]')
+            .joins('INNER JOIN namespaces as project_namespaces ON project_namespaces.id = projects.namespace_id')
+        else
+          namespaces = ::Namespace.reorder(nil).where('namespaces.id = projects.namespace_id')
+          ::Gitlab::ObjectHierarchy.new(namespaces, options: { skip_ordering: true }).roots
+        end
       end
       # rubocop: enable CodeReuse/ActiveRecord
 
@@ -87,6 +93,11 @@ module EE
         ENV['DISABLE_SHARED_RUNNER_BUILD_MINUTES_LIMIT'].to_s != 'true'
       end
 
+      def traversal_ids_enabled?
+        ::Feature.enabled?(:sync_traversal_ids, default_enabled: :yaml) &&
+          ::Feature.enabled?(:traversal_ids_for_quota_calculation, type: :development, default_enabled: :yaml)
+      end
+
       override :pre_assign_runner_checks
       def pre_assign_runner_checks
         super.merge({

ee/config/feature_flags/development/traversal_ids_for_quota_calculation.yml

+---
+name: traversal_ids_for_quota_calculation
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/56760
+rollout_issue_url:
+milestone: "13.11"
+type: development
+group: group::continuous integration
+default_enabled: false

ee/spec/services/ci/register_job_service_spec.rb

@@ -46,7 +46,22 @@ RSpec.describe Ci::RegisterJobService do
             shared_runners_seconds: runners_minutes_used * 60)
         end
 
-        it { is_expected.to be_kind_of(Ci::Build) }
+        context 'with flags enabled' do
+          before do
+            stub_feature_flags(sync_traversal_ids: true)
+            stub_feature_flags(traversal_ids_for_quota_calculation: true)
+          end
+
+          it { is_expected.to be_kind_of(Ci::Build) }
+        end
+
+        context 'with flag disabled' do
+          before do
+            stub_feature_flags(traversal_ids_for_quota_calculation: false)
+          end
+
+          it { is_expected.to be_kind_of(Ci::Build) }
+        end
       end
 
       shared_examples 'does not return a build' do |runners_minutes_used|
@@ -55,7 +70,22 @@ RSpec.describe Ci::RegisterJobService do
             shared_runners_seconds: runners_minutes_used * 60)
         end
 
-        it { is_expected.to be_nil }
+        context 'with flags enabled' do
+          before do
+            stub_feature_flags(sync_traversal_ids: true)
+            stub_feature_flags(traversal_ids_for_quota_calculation: true)
+          end
+
+          it { is_expected.to be_nil }
+        end
+
+        context 'with flag disabled' do
+          before do
+            stub_feature_flags(traversal_ids_for_quota_calculation: false)
+          end
+
+          it { is_expected.to be_nil }
+        end
       end
 
       context 'when limit set at global level' do