Re: Why is undo backed with redo for GTT

Hello!

Rollback information needs to be stored, for example for rolling back to a savepoint.
Rollback information is stored in rollback segments, which are stored in normal/undo tablespaces.
Changes to normal/undo tablespaces are normally logged - so far Oracle hasn't made a separate mechanism for handling DML on GTTs.

That's my understanding. In the future it could change..

Tanel.

"Rene Nyffenegger" <rene.nyffenegger_at_gmx.ch> wrote in message news:b3svke$1oju4r$1_at_ID-82536.news.dfncis.de...
> Hello
>
> One of the benefits of global temporary tables (gtt) is that it does not
> generate as much redo as 'normal' tables (See also a paralell thread on
> c.d.o.s). However, ggt's do generate undo which is backed by redo. Now, I
do
> understand why the undo is necessary, but I don't understand why this undo
> must be backed by redo. In case of a crash, only the structure of the gtt
> must be recovered, not its content. So, it seems to me, that there is
> nothing to be rolled back on the ggt, hence the undo generated for the ggt
> needs not be recovered.
>
> What am I missing?
>
>
> Thanks
> Rene Nyffenegger
>
>
>
> --
> no sig today
>
>
Received on Sun Mar 02 2003 - 08:04:21 CST