[Zope] Making transactions un-undoable ?

Hi, I have a Zope site which interacts with a relational database (PostgreSQL). My obvious problem is that when some transactions are undone, concerned Zope objects are not synchronized anymore with the database, as SQL commands can't be undone. My question is : is there any way to make a specific transaction not undoable (without using a specific storage which may prohibit undo) ?? Thanks, Thierry -- Linux every day, keeps Dr Watson away... http://gpc.sourceforge.net -- http://www.ulthar.net