Isolate descendant query in CTE

app/models/namespaces/traversal/linear_scopes.rb

@@ -105,27 +105,32 @@ module Namespaces
             :traversal_ids,
             'LEAD (namespaces.traversal_ids, 1) OVER (ORDER BY namespaces.traversal_ids ASC) next_traversal_ids'
           )
-          cte = Gitlab::SQL::CTE.new(:base_cte, base)
+          base_cte = Gitlab::SQL::CTE.new(:base_cte, base)
 
           namespaces = Arel::Table.new(:namespaces)
-          records = unscoped
-            .with(cte.to_arel)
-            .from([cte.table, namespaces])
 
           # Bound the search space to ourselves (optional) and descendants.
           #
           # WHERE (base_cte.next_traversal_ids IS NULL OR base_cte.next_traversal_ids > namespaces.traversal_ids)
           #   AND next_traversal_ids_sibling(base_cte.traversal_ids) > namespaces.traversal_ids
-          records = records
-            .where(cte.table[:next_traversal_ids].eq(nil).or(cte.table[:next_traversal_ids].gt(namespaces[:traversal_ids])))
-            .where(next_sibling_func(cte.table[:traversal_ids]).gt(namespaces[:traversal_ids]))
+          records = unscoped
+            .from([base_cte.table, namespaces])
+            .where(base_cte.table[:next_traversal_ids].eq(nil).or(base_cte.table[:next_traversal_ids].gt(namespaces[:traversal_ids])))
+            .where(next_sibling_func(base_cte.table[:traversal_ids]).gt(namespaces[:traversal_ids]))
 
           #   AND base_cte.traversal_ids <= namespaces.traversal_ids
-          if include_self
-            records.where(cte.table[:traversal_ids].lteq(namespaces[:traversal_ids]))
-          else
-            records.where(cte.table[:traversal_ids].lt(namespaces[:traversal_ids]))
-          end
+          records = if include_self
+                      records.where(base_cte.table[:traversal_ids].lteq(namespaces[:traversal_ids]))
+                    else
+                      records.where(base_cte.table[:traversal_ids].lt(namespaces[:traversal_ids]))
+                    end
+
+          records_cte = Gitlab::SQL::CTE.new(:descendants_cte, records)
+
+          unscoped
+            .unscope(where: [:type])
+            .with(base_cte.to_arel, records_cte.to_arel)
+            .from(records_cte.alias_to(namespaces))
         end
 
         def next_sibling_func(*args)

spec/support/shared_examples/namespaces/traversal_scope_examples.rb

@@ -213,6 +213,12 @@ RSpec.shared_examples 'namespace traversal scopes' do
 
       it { is_expected.to contain_exactly(deep_nested_group_1, deep_nested_group_2) }
     end
+
+    context 'with offset and limit' do
+      subject { described_class.where(id: [group_1, group_2]).offset(1).limit(1).self_and_descendants }
+
+      it { is_expected.to contain_exactly(group_2, nested_group_2, deep_nested_group_2) }
+    end
   end
 
   describe '.self_and_descendants' do
@@ -242,6 +248,19 @@ RSpec.shared_examples 'namespace traversal scopes' do
 
       it { is_expected.to contain_exactly(deep_nested_group_1.id, deep_nested_group_2.id) }
     end
+
+    context 'with offset and limit' do
+      subject do
+        described_class
+          .where(id: [group_1, group_2])
+          .limit(1)
+          .offset(1)
+          .self_and_descendant_ids
+          .pluck(:id)
+      end
+
+      it { is_expected.to contain_exactly(group_2.id, nested_group_2.id, deep_nested_group_2.id) }
+    end
   end
 
   describe '.self_and_descendant_ids' do