AI: address issue #445

backend/app/services/counts_table_query.rb

@@ -182,7 +182,7 @@ class CountsTableQuery
     order = sort_sql { detail_expression(_1) }
     query = query.order(Arel.sql((order + ['v.id ASC']).join(', ')))
         .limit(limit).offset((page - 1) * limit)
-    query = query.includes(:external_tag) if @definition.resource == 'nico_tags'
+    query = query.preload(:external_tag) if @definition.resource == 'nico_tags'
     rows = query.to_a
     if ['posts', 'tags'].include?(@definition.resource)
       point = population.history ? population.at :

backend/spec/requests/counts_table_spec.rb

@@ -74,6 +74,25 @@ RSpec.describe 'Counts table API', type: :request do
       end
     end
 
+    it 'preloads external names separately for aliased link-change details' do
+      statements = []
+      listener = lambda do |_name, _start, _finish, _id, payload|
+        statements << payload[:sql]
+      end
+      ActiveSupport::Notifications.subscribed(listener, 'sql.active_record') do
+        result = query(axis('changed_field', 'linked_tags'))
+        expect(versions(result)).to eq([2, 3])
+        expect(result.fetch('versions').map { _1.fetch('name') })
+            .to eq(['nico:beta', 'nico:beta'])
+      end
+
+      details = statements.find { _1.include?('AS counts_latest') }
+      expect(details).not_to be_nil
+      expect(details).not_to include('JOIN `external_tags`')
+      names = statements.select { _1.match?(/SELECT .* FROM `external_tags`/) }
+      expect(names.length).to eq(1)
+    end
+
     it 'advertises the legacy field, label and default columns only' do
       get '/counts/definitions/nico_tags', params: { locale: 'ja' }
       expect(response).to have_http_status(:ok)