Hi guys,
We have a long-running query (CTAS) that throws up ORA-01555. This is
the only query running against the database, which is Oracle9i
(9.2.0.6). Also, automatic undo is turned off on instructions from the
application vendor. Increasing the rollback tablespace makes this error
go away although the high water mark does not justify the increase in
tablespace size.

My question is: What are all the possible causes of this error and what
can be done in each case?

Thanks.