Add full index on namespaces for type and id and remove partial index

db/post_migrate/20211006174114_add_namespace_index_on_type_sync.rb

+# frozen_string_literal: true
+
+class AddNamespaceIndexOnTypeSync < Gitlab::Database::Migration[1.0]
+  FULL_INDEX_NAME = 'index_namespaces_on_type_and_id'
+  PARTIAL_INDEX_NAME = 'index_namespaces_on_type_and_id_partial'
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_index :namespaces, [:type, :id], name: FULL_INDEX_NAME
+
+    remove_concurrent_index_by_name :namespaces, name: PARTIAL_INDEX_NAME
+  end
+
+  def down
+    add_concurrent_index(:namespaces, [:type, :id], where: 'type IS NOT NULL', name: PARTIAL_INDEX_NAME)
+
+    remove_concurrent_index_by_name :namespaces, name: FULL_INDEX_NAME
+  end
+end

db/schema_migrations/20211006174114

+15d1bc08a87241b4217278ce8214f41d1d3c0cc4c26a3e659f395a602d139758
\ No newline at end of file

db/structure.sql

@@ -25834,7 +25834,7 @@ CREATE INDEX index_namespaces_on_shared_and_extra_runners_minutes_limit ON names
 
 CREATE INDEX index_namespaces_on_traversal_ids ON namespaces USING gin (traversal_ids);
 
-CREATE INDEX index_namespaces_on_type_and_id_partial ON namespaces USING btree (type, id) WHERE (type IS NOT NULL);
+CREATE INDEX index_namespaces_on_type_and_id ON namespaces USING btree (type, id);
 
 CREATE INDEX index_namespaces_public_groups_name_id ON namespaces USING btree (name, id) WHERE (((type)::text = 'Group'::text) AND (visibility_level = 20));