And a different good morning to you Norman,

> If I may be so bold ....

Of course, and thank you for the detailed and complete description of a
mechanism I glossed over irresponsibly.

> As long as the DBA correctly sizes the UNDO tablespace and correctly
> sets the UNDO_RETENTION parameter to a decent enough value, data changes
> are able to be rolled back happily all the time.
>
> If the DBA failed miserably in his/her duties, the ORA-01555 Snapshot
> too old" errors are the result. And are most irritating. Long running
> SELECTS - batch reports for example - tend to show up this error mostly.

Ha ha ha! You don't get month end this month because your DBA screwed
up! Try Firebird next time.

Cheers,

Ann