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Home -> Community -> Mailing Lists -> Oracle-L -> Re: Datawarehouse
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.
Regards,
Madhavan
IBM Corporation
>From: Joe Frohne <joe_at_rawsonoaks.com>
>Reply-To: ORACLE-L_at_fatcity.com
>To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
>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
>
>--
>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> Joe Frohne joe_at_rawsonoaks.com
> OCP Database Administrator www.rawsonoaks.com
>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>
>--
>Author: Joe Frohne
> INET: joe_at_rawsonoaks.com
>
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