Re: DROP COLUMN uses rollback?

Yes, but this particular bit of DDL is doing real work on your data. A 'drop column' means 'read a row; remove the data associated with the column being dropped; re-save the shortened row'. There's data manipulation going on here, and that generates undo/rollback.

If you really don't want to use rollback, use the 'set unused' option for the column. That is a purely data dictionary operation. The column data stays within the row, yet is totally inaccessible (and permanently so). Since it stays within the row, no data manipulation is going on, and hence no rollback is required (apart from the little bit associated with the data dictionary changes).

Regards
HJR "Stephen B" <stephen.bell_at_cgi.ca> wrote in message news:LEoL8.6678$W74.1398920_at_news20.bellglobal.com...
> Hi all,
>
> I've been trying to drop a column in a fairly large table I have (alter
> table xx drop column yy)
> After each of two initial attempts at this I received an "unable to extend
> rollback segment nn" error...
>
> There appear to be no active transactions so it seems that my transaction
is
> causing the rollback...
>
> I didn't think a DDL statement would do this?
>
> Any thoughts appreciated,
>
> Steve
>
>
Received on Wed Jun 05 2002 - 15:33:37 CDT