Integration

Hi,

what is the best philosophy about storing large xml data of BPEL Process?
i mean - i'm creatin business process in bpel and one of it's variables is XML document, that can grow to large size during process run .. what is the best way to store it? let the BPEL PM do it? or have only some id of this document in the process variable and have document stored in separate db as xml type?
I'm thinking of this, because i expect whole xml variable in bpel process is loaded from bpel database every time any element is accessed .. and this could be limitating for large data and many instances .. so i see storing xml document in xml database as better philosophy

thanks for advices, ideas ...
Tomas