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Field based modelling in SAP BW4

Hi All,

i am asking myself a very general question as i am developing since a couple of days with BW4.

Why would i develop any layer (unless the composite provider for the virtual layer) with infoObjects?
Following the LSA principles - and by reviewing the SAP BW4 business content we have following situation

  • Corperate Mem. Leyer (aDSO): Field based
  • Integrated DWH Layler (InfoSource +aDSO) : InfoObjects
  • Virtual Data Mart Layer : InfoObjects

For me this pointless. I am not giving any end-user access on aDSO level, so why would i develop them by using InfoObjects?

The only advise i found was this

https://help.sap.com/doc/saphelp_nw75/7.5.5/en-US/66/a0e6908ddf406783807af1cb3e02f8/frameset.htm

But i don't feel satisfied with this.

Thanks a lot for discussing this with me.

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4 Answers

  • Best Answer
    Posted on Jun 26, 2019 at 01:41 PM

    Hi,

    This can be answered through the source of data and the BI content.

    For instance; considering standard ERP processes like SD, MM, FI, CO etc. You load material or customer based transactional data to your BW/4HANA environment.

    By using 0MATERIAL and 0CUSTOMER characteristics you simply make your development easier. If you have a field based modelling with MATNR and KUNNR, you have to create joins of attributes, texts, hierarchies for all of your process based models again and again. Also, the administration and maintenance should also be considered.

    Moreover, BI content already delivers pre-configured models out of the box. I don't see any reasons to create all of them from scratch with field based modelling.

    If you working with non-SAP data (which doesn't have a BI content solution); then field based modelling makes sense. However, for repeating fields in each model I still prefer to use characteristics to have the advantage of them.

    Regards,
    Erdem

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  • Posted on Jun 26, 2019 at 02:06 PM

    Hi Sven,

    One issue I encountered was that, if you only use InfoObjects at the composite level, you may encounter errors (forbidden chararacters for instance) only at this level and when the data is queried. This could make the analysis of the issue and the correction of the erroneous data difficult.

    Of course, you can validate your data at one of your DW layer but probably not for all the fields and, anyway, surprises can happen.

    Regards,

    Frederic

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  • Posted on Jun 26, 2019 at 04:05 PM

    Hi Sven

    Performance also a very good reason. The presence of field-based components in the query impacts performance (lack of parallelisation, lack of OLAP cache usage, joins at runtime etc.) and query functionality (e.g. lack of HANA pushdown for exception aggregation).

    Regards, Carlos

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  • Posted on Jun 27, 2019 at 08:02 AM

    Hello together

    thanks a lot for your input.

    @ Erdem: For the BI-content. Yes i agree. A lot of work is already done by using InfoObjects. No need to do that all again using only fields.

    "If you have a field based modelling with MATNR and KUNNR, you have to create joins of attributes, texts, hierarchies for all of your process based models again and again. Also, the administration and maintenance should also be considered." -> in what example should this happen? If i have complex business logic ?

    @ Frederic: Luckily i don't have this issue now.

    @ Carlos: Performance may is something i have not yet considered as important (HANA ??) But you're giving me a good hint. Does it mean as soon as you have one field only all the parallelisation, cache, pushdowns will not happen?

    Another question came to my mind while working. I have not yet understood in BW4 if SID generation in a aDSO will happen or not. If so, where can i set this?

    Thanks a lot in advance and looking forward to hear from you.

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    • Hi Sven,

      That part refers to data models which gets data from SAP systems. If you're getting data from generic datasources which doesn't have a corresponding BI content; you don't need InfoObjects for all fields. However for standard fields like material, customer etc. it's better to use existing characteristics.

      Yes, SIDs are generated. That's another advantage of InfoObjects which helps inners joins to be used instead of left outer.

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