This article from the GAE Java Persistence Blog, Executing Batch
Gets, might help:
http://gae-java-persistence.blogspot.com/2009/10/executing-batch-gets.html
That blog seems like the missing manual for using the datastore with
Java. I've found many of very useful tips and examples in it, but I
I've had trouble with the .getById methods, so I do it like this,
which seems to work reliably:
query = pm.newQuery(MyClass.class);
query.setFilter(_ID == :keyList); //_ID is the PK
ListMyClass results = (ListMyClass)query.execute(Keys); //
Keys
