Xref: alice comp.databases.oracle.server:20273
Message-ID: <354EE02F.8F732338@compuserve.com>
Date: Tue, 05 May 1998 10:47:27 +0100
From: Rod Corderey <Lane_Associates@compuserve.com>
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To: Larry Schenavar <schenavar@northstate.net>
Subject: Re: Help needed with big table
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Larry,

can you post the actual table layout?  

The fact that the table contains 8M rows and has a concatenated key is
less important than the basis of data retrieval from it. 

ie what retrieval conditions are applied in the normal SQL.

   what is the probable size of data set being retreived at any point
in  time?

eg if index is made up of col1, col2, col3 but a dataset of say 150 rows
is conventionaly retreived with conditions only on col2 and col3 then
the result will be very inefficient access via that particular index.

It is a common problem where an index exists to support the primary key
of a table but the back navigation of the database for business support
sometimes requires alternative indexation.

regards

Rod Corderey

Lane Associates
Lane_Associates@Compuserve.com
http://www.Lane-Associates.com


Larry Schenavar wrote:
> 
> Hello,
> 
> I have a table with 4 columns.  It contains 8 million records and the key is
> three of the columns.  It is very slow to access.  Does anyone have any
> recommendation to increase the performance.  Is indexing the three columns a
> waste?
> 
> ==============================
> Larry Schenavar
> Infrastructure Specialist /DB
> Electronic Data Systems, Inc
> 
> Email:   schenavar@northstate.net
> ==============================