Avoid extra touch queries when counter cache is updated

Since counter cache handles touch option too.

activerecord/lib/active_record/associations/builder/belongs_to.rb

@@ -81,12 +81,18 @@ module ActiveRecord::Associations::Builder # :nodoc:
         BelongsTo.touch_record(record, record.send(changes_method), foreign_key, n, touch, belongs_to_touch_method)
       }}
 
-      unless reflection.counter_cache_column
+      if reflection.counter_cache_column
+        touch_callback = callback.(:saved_changes)
+        update_callback = lambda { |record|
+          instance_exec(record, &touch_callback) unless association(reflection.name).target_changed?
+        }
+        model.after_update update_callback, if: :saved_changes?
+      else
         model.after_create callback.(:saved_changes), if: :saved_changes?
+        model.after_update callback.(:saved_changes), if: :saved_changes?
         model.after_destroy callback.(:changes_to_save)
       end
 
-      model.after_update callback.(:saved_changes), if: :saved_changes?
       model.after_touch callback.(:changes_to_save)
     end
 

activerecord/test/cases/associations/belongs_to_associations_test.rb

@@ -616,8 +616,10 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     debate.touch(time: time)
     debate2.touch(time: time)
 
-    reply.parent_title = "debate"
-    reply.save!
+    assert_queries(3) do
+      reply.parent_title = "debate"
+      reply.save!
+    end
 
     assert_operator debate.reload.updated_at, :>, time
     assert_operator debate2.reload.updated_at, :>, time
@@ -625,8 +627,10 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     debate.touch(time: time)
     debate2.touch(time: time)
 
-    reply.topic_with_primary_key = debate2
-    reply.save!
+    assert_queries(3) do
+      reply.topic_with_primary_key = debate2
+      reply.save!
+    end
 
     assert_operator debate.reload.updated_at, :>, time
     assert_operator debate2.reload.updated_at, :>, time