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Re: Datawarehouse

From: Madhavan Amruthur <>
Date: Fri, 21 Jul 2000 09:43:41 PDT
Message-Id: <>

Hi Joe,
Yes as far as I know to use the star_transformation you have to have a bitmap index.

The typical scenario would be you will have the different grades in a grade table and the grade id would be in the fact table and other dimension id's will be in the fact table and you will have a bitmap index for each of those dimension id's in the fact table.

The star transformation will then pick the bitmap index of each dimension id and then do a BITMAP AND of the id's and then a bitmap MERGE to get the result from the fact table.

Hope this helps.

IBM Corporation

>From: Joe Frohne <>
>To: Multiple recipients of list ORACLE-L <>
>Subject: Datawarehouse
>Date: Fri, 21 Jul 2000 06:48:19 -0800
>Hi Listers,
>I have a quick question about setting up a star schema datawarehouse using
>star_transformation_enabled. I have a fact table and several dimension
>tables. My fact table is a personal table and some of the dimension
>tables are grades and test scores. The fact table has the students id and
>it is linked to all of the dimension tables with the id field. To use the
>star transformation I need to have a bitmapped index on the id field in
>the personal table. This is going to be a totaly unique field.
>The question is, what is the downside of a bitmapped index on such a
>field? Is my thought process correct that there needs to be a bitmaped
>index on this field to utilize the star transformation?
>Thank You for any insight!
> Joe Frohne
> OCP Database Administrator
>Author: Joe Frohne
>Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
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Get Your Private, Free E-mail from MSN Hotmail at Received on Fri Jul 21 2000 - 11:43:41 CDT

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