Re: METALINK and OWS

At 08:00 PM 6/12/00 -0800, you wrote:
>Oh, and I once had a query go from 30 minutes to 6 minutes by dropping an
>index....

Oh, sure, I've done that too, but at least that one followed the published rules...

>>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
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>>>
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>>>--
>>>Author: Rachel Carmichael
>>> INET: carmichr_at_hotmail.com
>>>
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>>--
>>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
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>
>________________________________________________________________________
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>--
>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
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Received on Tue Jun 13 2000 - 11:38:46 CDT