Re: How come oracle is always using only one of my indexes ?

From: Nuno Souto <nsouto_at_optushome.com.au.nospam>
Date: Thu, 23 Aug 2001 11:54:59 GMT
Message-ID: <3b84ec57.4648370@news>

On Wed, 22 Aug 2001 20:43:22 GMT, Brian Peasland <oracle_dba_at_qwest.net> wrote:

>
>> AFAIK, Oracle will neever use more than one index on one table in one
>> query.
>
>Correct!
>

Akshally, not quite. In older versions, it could do a thing called an "Index Merge". It still does, if you use the correct hint or combination of index types (bitmapped indexes spring to mind).

The old index merge was usually a killer of performance, I think that's why it was removed as a default. But it's still possible to "re-enable" it for special occasions.

Cheers
Nuno Souto
nsouto_at_optushome.com.au.nospam Received on Thu Aug 23 2001 - 06:54:59 CDT