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Home -> Community -> Mailing Lists -> Oracle-L -> Re: METALINK and OWS
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
>
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