i'm a programmer, not a dba. i need a mechanism to quickly make a snapshot of a database (oracle 11g XE) before i run migration. migration changes data, grants, DDL (tables, triggers, lexers, views ...
I tried exp utility to dump all database. Looks like this exports only the last version of data skipping undo log. Using flashback queries I see: 01466. 00000 - "unable to read data - table ...