Always use CTE for IssuableFinder counts

Since the CTE is faster than a subquery and the only reason we're using
a subquery is that the CTE can't handle sorting by certain attributes,
let's use the CTE always (when the feature flag is enabled) when
counting, since we can ignore ordering if we just want a count of
results.

2 files changed, 26 insertions, 33 deletions

diff --git a/spec/controllers/groups_controller_spec.rb b/spec/controllers/groups_controller_spec.rb
index 7d87b33e503..21e5122c06b 100644
--- a/spec/controllers/groups_controller_spec.rb
+++ b/spec/controllers/groups_controller_spec.rb
@@ -227,9 +227,7 @@ describe GroupsController do
 
     context 'searching' do
       before do
-        # Remove in https://gitlab.com/gitlab-org/gitlab-ce/issues/54643
-        stub_feature_flags(use_cte_for_group_issues_search: false)
-        stub_feature_flags(use_subquery_for_group_issues_search: true)
+        stub_feature_flags(attempt_group_search_optimizations: true)
       end
 
       it 'works with popularity sort' do
diff --git a/spec/finders/issues_finder_spec.rb b/spec/finders/issues_finder_spec.rb
index 34cb09942be..868caf748f4 100644
--- a/spec/finders/issues_finder_spec.rb
+++ b/spec/finders/issues_finder_spec.rb
@@ -659,7 +659,7 @@ describe IssuesFinder do
 
     before do
       allow(Gitlab::Database).to receive(:postgresql?).and_return(true)
-      stub_feature_flags(use_subquery_for_group_issues_search: true)
+      stub_feature_flags(attempt_group_search_optimizations: true)
     end
 
     context 'when there is no search param' do
@@ -690,11 +690,11 @@ describe IssuesFinder do
       end
     end
 
-    context 'when the use_subquery_for_group_issues_search flag is disabled' do
+    context 'when the attempt_group_search_optimizations flag is disabled' do
       let(:params) { { search: 'foo', attempt_group_search_optimizations: true } }
 
       before do
-        stub_feature_flags(use_subquery_for_group_issues_search: false)
+        stub_feature_flags(attempt_group_search_optimizations: false)
       end
 
       it 'returns false' do
@@ -702,6 +702,14 @@ describe IssuesFinder do
       end
     end
 
+    context 'when force_cte? is true' do
+      let(:params) { { search: 'foo', attempt_group_search_optimizations: true, force_cte: true } }
+
+      it 'returns false' do
+        expect(finder.use_subquery_for_search?).to be_falsey
+      end
+    end
+
     context 'when all conditions are met' do
       let(:params) { { search: 'foo', attempt_group_search_optimizations: true } }
 
@@ -711,72 +719,59 @@ describe IssuesFinder do
     end
   end
 
-  describe '#use_cte_for_search?' do
+  describe '#use_cte_for_count?' do
     let(:finder) { described_class.new(nil, params) }
 
     before do
       allow(Gitlab::Database).to receive(:postgresql?).and_return(true)
-      stub_feature_flags(use_cte_for_group_issues_search: true)
-      stub_feature_flags(use_subquery_for_group_issues_search: false)
+      stub_feature_flags(attempt_group_search_optimizations: true)
     end
 
     context 'when there is no search param' do
-      let(:params) { { attempt_group_search_optimizations: true } }
+      let(:params) { { attempt_group_search_optimizations: true, force_cte: true } }
 
       it 'returns false' do
-        expect(finder.use_cte_for_search?).to be_falsey
+        expect(finder.use_cte_for_count?).to be_falsey
       end
     end
 
     context 'when the database is not Postgres' do
-      let(:params) { { search: 'foo', attempt_group_search_optimizations: true } }
+      let(:params) { { search: 'foo', force_cte: true, attempt_group_search_optimizations: true } }
 
       before do
         allow(Gitlab::Database).to receive(:postgresql?).and_return(false)
       end
 
       it 'returns false' do
-        expect(finder.use_cte_for_search?).to be_falsey
+        expect(finder.use_cte_for_count?).to be_falsey
       end
     end
 
-    context 'when the attempt_group_search_optimizations param is falsey' do
+    context 'when the force_cte param is falsey' do
       let(:params) { { search: 'foo' } }
 
       it 'returns false' do
-        expect(finder.use_cte_for_search?).to be_falsey
-      end
-    end
-
-    context 'when the use_cte_for_group_issues_search flag is disabled' do
-      let(:params) { { search: 'foo', attempt_group_search_optimizations: true } }
-
-      before do
-        stub_feature_flags(use_cte_for_group_issues_search: false)
-      end
-
-      it 'returns false' do
-        expect(finder.use_cte_for_search?).to be_falsey
+        expect(finder.use_cte_for_count?).to be_falsey
       end
     end
 
-    context 'when use_subquery_for_search? is true' do
-      let(:params) { { search: 'foo', attempt_group_search_optimizations: true } }
+    context 'when the attempt_group_search_optimizations flag is disabled' do
+      let(:params) { { search: 'foo', force_cte: true, attempt_group_search_optimizations: true } }
 
       before do
-        stub_feature_flags(use_subquery_for_group_issues_search: true)
+        stub_feature_flags(attempt_group_search_optimizations: false)
       end
 
       it 'returns false' do
-        expect(finder.use_cte_for_search?).to be_falsey
+        expect(finder.use_cte_for_count?).to be_falsey
       end
     end
 
     context 'when all conditions are met' do
-      let(:params) { { search: 'foo', attempt_group_search_optimizations: true } }
+      let(:params) { { search: 'foo', force_cte: true, attempt_group_search_optimizations: true } }
 
       it 'returns true' do
-        expect(finder.use_cte_for_search?).to be_truthy
+        expect(finder.use_cte_for_count?).to be_truthy
       end
     end
   end