Re: bitmap index Q.

From: Charlie Mengler <charliem_at_mwh.com>
Date: Fri, 28 Apr 2000 14:09:30 -0700
Message-Id: <10481.104480@fatcity.com>

Our experience with bitmapped indexes is "mixed". I suggest that you do the following -

1) Make note of the size of the bit mapped index after a clean rebuild
2) Do the inserts & such.
3) Make note of the size of the bit mapped index

You'll likely see a LARGE, LARGE increase in the size of the bit mapped index.

We reported this behavior to Oracle. They said to drop the index prior to the inserts & rebuild then once the inserts are done.

HTH! Lisa_Koivu_at_gelco.com wrote:
>
> Hola!
>
> One of our data marts here had awful performance yesterday. The only thing that
> was different between yesterday and the previous days was that the load ran with
> all indexes, including bitmaps, on the tables. Only 10,000 rows were added -
> less than 1% change. The analyze was run for all tables to be hit by the
> reports. However performance really bit yesterday until the indexes were
> dropped and rebuilt.
>
> In class I remember talking about the tradeoff between a fast load/building
> indexes and a slow load/leaving indexes up. Has anyone seen this type of
> behavior before? I can not say for sure that the load is not updating the
> fields the bitmap indexes were on.
>
> Any comments are appreciated.
>
> Lisa 'Almost Certified' Koivu
>
> --
> Author:
> INET: Lisa_Koivu_at_gelco.com
>
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-- 
Charlie Mengler                       Maintenance Warehouse  
charliem_at_mwh.com                      5505 Morehouse Drive   
858-552-6229                          San Diego, CA 92121    
If you don't use vi, then you shouldn't be working on UNIX!

Received on Fri Apr 28 2000 - 16:09:30 CDT