| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
 |
 | |||
| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
|
| |||
Home -> Community -> Mailing Lists -> Oracle-L -> Re: METALINK and OWS
Nicholas,
Sorry... I thought most people knew this. Oracle says that if a query will return more than 20% of the rows of a table, it will use a full table scan. So you DON'T tune it to use an index. In fact, as of 8i, I believe Oracle now recommends that if a query returns as little as 3-5% of a table, a full table scan is the way to go.
As for places to look for tuning information:
Oracle docs -- the Tuning Guide
Advanced Oracle Tuning and Adminstration -- Oracle Press, Loney, Aronoff and
Sonawalla
Rachel
>From: Nicholas Tufar <ntufar_at_chemist.gen.tr>
>Reply-To: ORACLE-L_at_fatcity.com
>To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
>Subject: Re: METALINK and OWS
>Date: Sat, 10 Jun 2000 14:15:36 -0800
>
> > if a query is going
> > to return 30% of the rows in a table, how would you tune it? [Answer
>I
> > got: hint it to use an index. EHHHHH! Next contestant please!])
>
>And what is the right answer?
>It would be really nice to know. Or just point out where I can read
>about it.
>
>Nicholas
>--
>Author: Nicholas Tufar
> INET: ntufar_at_chemist.gen.tr
>
>Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
>San Diego, California -- Public Internet access / Mailing Lists
>--------------------------------------------------------------------
>To REMOVE yourself from this mailing list, send an E-Mail message
>to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
>the message BODY, include a line containing: UNSUB ORACLE-L
>(or the name of mailing list you want to be removed from). You may
>also send the HELP command for other information (like subscribing).
 |
 |