Extent<T> getExtent(
  Class<T> persistenceCapableClass, 
  boolean subclasses
)

The PersistenceManager manages a collection of instances in the data store based on the class of the instances. This method returns an Extent of instances in the data store that might be iterated or given to a Query. The Extent itself might not reference any instances, but only hold the class name and an indicator as to whether subclasses are included in the Extent.

Note that the Extent might be very large.