Re: DROP COLUMN uses rollback?

That makes perfect sense...thank you!
I'm familiar with the UNUSED option, but I'll need to free up the space eventually...this particular database is in development and will ultimately be deployed accross the country...unfortunately space is a consideration in deployment.

Thank you especially Howard, for taking the time to clearly delineate why this particular type of DDL requires rollback.

Much appreciated,

Steve

"Howard J. Rogers" <dba_at_hjrdba.com> wrote in message news:adlsje$boi$1_at_lust.ihug.co.nz...
> Yes, but this particular bit of DDL is doing real work on your data. A
'drop
> column' means 'read a row; remove the data associated with the column
being
> dropped; re-save the shortened row'. There's data manipulation going on
> here, and that generates undo/rollback.
>
> If you really don't want to use rollback, use the 'set unused' option for
> the column. That is a purely data dictionary operation. The column data
> stays within the row, yet is totally inaccessible (and permanently so).
> Since it stays within the row, no data manipulation is going on, and hence
> no rollback is required (apart from the little bit associated with the
data
> dictionary changes).
>
> Regards
> HJR
>
>
> "Stephen B" <stephen.bell_at_cgi.ca> wrote in message
> news:LEoL8.6678$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 Thu Jun 06 2002 - 07:18:35 CDT