Re: DROP COLUMN uses rollback?

Stephen B wrote:
> 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?

This one does.

Not only does it update the table definition, it also updates every record to physically remove the data for that column. Use:

        ALTER TABLE t1 SET UNUSED (c1, c2);
to only mark a column as unused.
It looks dropped, but the space for the column is still in use.

At a later time, use:

        ALTER TABLE t1 DROP UNUSED COLUMNS;
to actually free the space.

E. Received on Wed Jun 05 2002 - 15:00:04 CDT