Re: Star Schema Performance Problems?

8.0 Oracle and b-tree indexes.

Randy

Jonathan Lewis wrote:

> Which version of Oracle ?
> Are you talking about 8.1 and
> bitmapped star transformation,
> or 8.0 and concatenated b-tree
> indexing ?
>
> --
>
> Jonathan Lewis
> Yet another Oracle-related web site: http://www.jlcomp.demon.co.uk
>
> reash_at_attglobal.net wrote in message <39579D6A.69B88B94_at_attglobal.net>...
> >We are having Oracle performance problems with a star schema.
> >
> >We have a 16 million row fact table surrounded by a dozen small
> >dimension tables. If we run a report query joining the fact table with
> >several dimension tables that only restricts on the dimension tables, it
> >looks like Oracle is trying to do multiple scans of the fact table. If
> >we place the restriction on the fact table, then explain plan seems to
> >do something reasonable. In one case, the select ran 25 times faster if
> >the restriction was placed on the fact table.
> >
> >Is this normal? Is there something I should know about Oracle and Star
> >Schemas?
> >
> >Thanks
> >Randy Eash
> >
Received on Mon Jun 26 2000 - 00:00:00 CDT