Re: Faster imports

Disable archiving, specifying unrecoverable option, and specifying NOLOGGING are different things. None of them have anything to do with the rollback segments.

Specifying unrecoverable is used in CREATE TABLE AS, and does not log (in the redologs) the new entries into the table, making them unrecoverable, but speeding up the creation of the table.

Specifying a table as nologging, means that when using sqlloader or a direct insert, the data is not logged (in the redologs). Therefore, if there is a database crash, this table is unrecoverable, but the inserts are faster.

I don't see how any of these would help during an import using the import utility. If you used sqlloader, you could save some time by using the NOLOGGIN option on tables.

• Paul

Russ Frier wrote:

> Isn't it true that if you specify 'unrecoverable', you shouldn't have to disable
> archiving?
>
> rob van laarhoven wrote:
>
> > This is what I can think of. Maybe one of the suggestions can be used in
> > your shop.
> >
> > - Disable archiving, but you'll have to make a backup immediatly after
> > enabling archiving.
> > - Place dmp file on a different disk than redo-logs, rollback segment, data
> > tablespaces; reducing IO contention.
> > - Create character-separated file and use direct sqlload, this is faster
> > than export.
> > - start database with a init.ora designed to speed up an import
> > - Use a lot of (5?) big redo logs(10Mb?).
> >
> > One of the reasons why the unrecoverable option is so much faster is that
> > it's bypassing the rollback segments. This can not be done using import. The
> > dml done with the unrecoverable option is lost after a database recovery.
> >
> > Regards,
> > Rob.
> >
> > Rob.
Received on Wed Jan 19 2000 - 16:27:36 CST