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Asked: 2026-06-01T11:57:17+00:00

i have a simple question in the objectify documentation it says that Only get(),

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i have a simple question

in the objectify documentation it says that “Only get(), put(), and delete() interact with the cache. query() is not cached”
http://code.google.com/p/objectify-appengine/wiki/IntroductionToObjectify#Global_Cache.

what i’m wondering – if you have one root entity (i did not use @Parent due to all the scalability issues that it seems to have) that all the other entities have a Key to, and you do a query such as 

ofy.query(ChildEntity.class).filter("rootEntity", rootEntity).list()

is this completely bypassing the cache?

If this is the case, is there an efficient caching way to do a query on conditions – or for that matter can you cache a query with a parent where you would have to make an actual ancestor query like the following

Key<Parent> rootKey = ObjectifyService.factory().getKey(root)
ofy.query(ChildEntity.class).ancestor(rootKey)

Thank you

as to one of the comments below i’ve added an edit

sample dao (ignore the validate method – it just does some null & quantity checks):

this is a sample find all method inside a delegate called from the DAO that the request factory ServiceLocator is using

public List<EquipmentCheckin> findAll(Subject subject, Objectify ofy, Event event) {
  final Business business = (Business) subject.getSession().getAttribute(BUSINESS_ATTRIBUTE);
  final List<EquipmentCheckin> checkins = ofy.query(EquipmentCheckin.class).filter(BUSINESS_ATTRIBUTE, business)
    .filter(EVENT_CONDITION, event).list();
  return validate(ofy, checkins);
}

now, when this is executed i find that the following method is actually being called in my AbstractDAO. 

/**
* 
* @param id
* @return
*/
public T find(Long id) {
  System.out.println("finding " + clazz.getSimpleName() + " id = " + id);
  return ObjectifyService.begin().find(clazz, id);
}
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1 Answer

  1. Editorial Team

    Yes, all queries bypass Objectify’s integrated memcache and fetch results directly from the datastore. The datastore provides the (increasingly sophisticated) query engine that understands how to return results; determining cache invalidation for query results is pretty much impossible from the client side.

    On the other hand, Objectify4 does offer a hybrid query cache whereby queries are automagically converted to a keys-only query followed by a batch get. The keys-only query still requires the datastore, but any entity instances are pulled from (and populate on miss) memcache. It might save you money.

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