Are fetch () request and iteration the same in App Engine?

Question

With App Engine version 1.3.6 released in August-17-2010 , the 1000 fetch() element limit has been removed.

Does this mean that ModelClass.all().fetch(limit=99999999999) and [e for e in ModelClass.all()] equivalent?

If they differ from each other, they can differ in a subtle way. For example, does the number of RPC calls match?

Answer 1

Although the limit of 1000 objects has been removed from the selection, you still need to provide an explicit upper bound. Of course, if you make it big enough, you will get all of your entities.

The iterator approach proposed above is functionally equivalent (if the limit passed to the sample is large enough to get all entities). However, they have different performance characteristics. In particular, an iterator retrieves nodes with a small number of objects at a time. If you have a large number of objects, then the version using the iterator will do many more RPCs.