Re: METALINK and OWS

Oh, and I once had a query go from 30 minutes to 6 minutes by dropping an index....

>From: Regina Harter <rharter_at_emc-inc.com>
>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: Mon, 12 Jun 2000 10:51:04 -0800
>
>I hate to dispute this, and I really can't support it except by the result,
>but I just improved the performance of a query which selected almost 40% of
>the rows by ADDING an index (on 8.0.6).
>
>Regina
>Camarillo, California
>
>At 04:14 PM 6/11/00 -0800, you wrote:
>>WHOA! Slow down before you drop the indexes. Indexes are not totally
>>useless! It very much depends on the queries you run against your
>>database. If you are doing a mixture of queries, where some return single
>>rows or a very small subset of data, and some return a large number of
>>rows, you still should keep the indexes for the first type of query.
>>
>>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: Sun, 11 Jun 2000 14:17:51 -0800
>>>
>>> >
>>> > 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.
>>>
>>>A very valuable piece of information. How did I miss it!
>>>Now I know what I am going to do on Monday. I had a feeling that
>>>all those indeces are useless, now I know why they are.
>>>Thank you very much.
>>>
>>>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).
>>
>>________________________________________________________________________
>>Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com
>>
>>--
>>Author: Rachel Carmichael
>> INET: carmichr_at_hotmail.com
>>
>>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).
>
>--
>Author: Regina Harter
> INET: rharter_at_emc-inc.com
>
>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).