When using a persistent space there are situations where not all the Entries need to be stored in the persistent store. You can define the Entry to be stored only in the space cache, without storing it also in the persistent store, by setting its persistent mode to false. This setting must be specified when the Entry has been created and before it has been written to the space. After the Entry has been written to the space you cannot change its persistent mode.
Transient Space objects are treated the same as persistent objects, but when you call the write operation, only persistent objects are saved to the persistent store. All space operations, including batch operations, are valid for transient Entries.
When using the Mirror Service or the DataPersister interface, you might not want to replicate all space Entries into the mirror service to be persistent or to be delivered to some external data source.
The Mirror Service/DataPersister do not persist or deliver to external data source an Entry that has been identified as transient.