Fix issue search optimization in GraphQL

This enables the CTE search optimization when searching issuables via
GraphQL.

When going through GraphQL resolvers, a symbol is passed in as the sort
param of the IssuesFinder. This fixes our search optimization which
depends on the given sort order to take symbols into account.

Changelog: fixed

app/finders/issuable_finder.rb

@@ -194,8 +194,7 @@ class IssuableFinder
   def use_cte_for_search?
     strong_memoize(:use_cte_for_search) do
       next false unless search
-      # Only simple unsorted & simple sorts can use CTE
-      next false if params[:sort].present? && !params[:sort].in?(klass.simple_sorts.keys)
+      next false unless default_or_simple_sort?
 
       attempt_group_search_optimizations? || attempt_project_search_optimizations?
     end
@@ -244,6 +243,10 @@ class IssuableFinder
     klass.all
   end
 
+  def default_or_simple_sort?
+    params[:sort].blank? || params[:sort].to_s.in?(klass.simple_sorts.keys)
+  end
+
   def attempt_group_search_optimizations?
     params[:attempt_group_search_optimizations]
   end

spec/finders/issues_finder_spec.rb

@@ -1199,6 +1199,14 @@ RSpec.describe IssuesFinder do
       end
     end
 
+    context 'when a non-simple sort is given' do
+      let(:params) { { search: 'foo', attempt_project_search_optimizations: true, sort: 'popularity' } }
+
+      it 'returns false' do
+        expect(finder.use_cte_for_search?).to be_falsey
+      end
+    end
+
     context 'when all conditions are met' do
       context "uses group search optimization" do
         let(:params) { { search: 'foo', attempt_group_search_optimizations: true } }
@@ -1217,6 +1225,24 @@ RSpec.describe IssuesFinder do
           expect(finder.execute.to_sql).to match(/^WITH "issues" AS #{Gitlab::Database::AsWithMaterialized.materialized_if_supported}/)
         end
       end
+
+      context 'with simple sort' do
+        let(:params) { { search: 'foo', attempt_project_search_optimizations: true, sort: 'updated_desc' } }
+
+        it 'returns true' do
+          expect(finder.use_cte_for_search?).to be_truthy
+          expect(finder.execute.to_sql).to match(/^WITH "issues" AS #{Gitlab::Database::AsWithMaterialized.materialized_if_supported}/)
+        end
+      end
+
+      context 'with simple sort as a symbol' do
+        let(:params) { { search: 'foo', attempt_project_search_optimizations: true, sort: :updated_desc } }
+
+        it 'returns true' do
+          expect(finder.use_cte_for_search?).to be_truthy
+          expect(finder.execute.to_sql).to match(/^WITH "issues" AS #{Gitlab::Database::AsWithMaterialized.materialized_if_supported}/)
+        end
+      end
     end
   end