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Aggregates on ODS

Former Member
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Hi all,

I have a doubt why can't we create aggregates on ODS, why only on Cube's?.

Please let me know.

Thanking you.

Best Regards

Satish

Accepted Solutions (0)

Answers (3)

Answers (3)

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hi Satish,

from the data modeling point of view, granularity... normaly ODS is used to store data in more detail level, document level. with mostly different document/transaction number for each record, aggregate won't effective (if we can create). to speed up performance in accessing ODS, indexing can be used.

Former Member
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SAP's view is that ODS are, as AHP mentions, a detail item data store and that most analysis/reporting is done against summarized data stored in InfoCubes.

Based on this viewpoint, SAP has not extended the aggregate creation tool to work with an ODS, but from a technical standpoint, however, there is no reason you couldn't have aggregates on a ODS.

Oracle and IBM provide mechanism's to create aggregates on a flat table ( Oracle calls them Materialized Views and IBM refers to them as Automatic Summary Tables). BW aggregates predate these capabilities and offer some other advantages, e.g. ability to build aggregates with different levels of hierarchies, or on fixed value, the ability to utilize the dimension tables of the base cube when the aggregate dimension matches a base cube dimension, etc.

If you want to some further info, Thomas Zurek, a BI Development Mgr at SAP, talked about some of this in a recent blog - /people/thomas.zurek/blog/2005/11/02/netweaver-bi-aka-bw-and-advanced-db-functionality-part-1

Former Member
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Hi Satish,

Let me explain a bit more. Aggregates is form structure point-of-view just another fact table (cube).

Since an ODS doesn't use a fact table it's not possible to use aggregates.

If you want less number of records read during ODS querying try to find a key which 'aggregates' more.

Regards,

Brian

Former Member
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ODS is flat Structure.

Nagesh