RE: Weirdness

From: Lord, David - C&S <David.Lord_at_hayscsg.com>
Date: Thu, 25 Oct 2001 00:30:28 -0700
Message-ID: <F001.003B3D4A.20011025004024@fatcity.com>

Depends whether each column has a separate index on it, or all columns are in a single concatenated index. An IOT is like the latter - it's only going to help if you are always using the same (or similar) access path.

Oracle doesn't go to a table if it can get all the values it needs from an index. So, I suspect that the performance of an IOT may not be any better than a suitable concatenated index. It simply saves you from storing the data twice.

> -----Original Message-----
> From: Kimberly Smith [mailto:kimberly.smith_at_gmd.fujitsu.com]
> Sent: 24 October 2001 18:55
> To: Multiple recipients of list ORACLE-L
> Subject: Weirdness
>
>
> Oracle 8.1.7.1 on HPUX 11
>
> I have a table that I have just indexed every column. This
> has improved the
> query performance however, its going to slow down the load.
> Thing that has
> me confused is that I tried this as an IOT and it actually
> hurt performance.
> This table is joined to another table 3xs. The table I made
> an IOT has >2
> million rows and the other table has >6 million rows.
> Shouldn't the IOT
> table have had similar performance to having every column indexed?
>
>
>
> ________________________________________
> Kimberly Smith
> GMD Fujitsu
> Database Administrator
> (503) 669-6050
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Kimberly Smith
> INET: kimberly.smith_at_gmd.fujitsu.com
>
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---

-- 
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-- 
Author: Lord, David - C&S
  INET: David.Lord_at_hayscsg.com

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Received on Thu Oct 25 2001 - 02:30:28 CDT