why are you looking for undo space for a session?
The undo is generated on master site (source table) during fast refresh of MV. The database especially undo tablespace which has fixed size, on master site is not in our control. Therefore, we want to get some guess as how much undo is being generated on local and remote sites during fast refresh of MV.
Can any body tell me why undo is being generated on remote site although DML operations are performed on local site during synchronization by MV?