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

From: Kenneth Koenraadt <plovmand_at_hotmail.com>
Date: Wed, 22 Aug 2001 18:30:23 GMT
Message-ID: <3b83f57b.1381008@news.mobilixnet.dk>

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

That would be insufficient : first you fetch two sets of rows by scanning 2 indexes and then you merge them. It is much better to fetchs the rows via one index scan and then filter those who do not satisfy the other clauses.

Regards,
Kenneth Koenraadt
Systems Consultant
Oracle DBA
plovmand@<no-spam>hotmail.com

On 22 Aug 2001 10:21:50 -0700, turboridelover_at_yahoo.com (DrowningPeople) wrote:

>I have a table with 12 columns, and I have thousands of random queries
>that could involve any different number of different columns. I have
>an index for each column. For those "AND-EQUAL" operations, I expect
>oracle to mergs lists of data returned from multiple index scans. But
>oracle is always using only one index (different one everytime). Can
>anyone tell me why?
>
>Thanks alot
Received on Wed Aug 22 2001 - 13:30:23 CDT