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SAP recommends more use of dimenions

Hi,

Why SAP recommneds more of use dimensions?

Thanks in advance

krish

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4 Answers

  • Best Answer
    Posted on Dec 07, 2011 at 05:25 AM

    Hi Kris,

    1. Generally cube is multi-dimensional table fact table located at middle surrounded by Dimension-tables.

    2. Taking the all info objects into one DIM or taking one InfoObject into different DIM is not the right process.

    3. Take the related objects into one dimension. But not more then 20% of the fact table.

    case1 : If we use single dimension -- Accessing of data is first hit to fact table after that DIM-table next SID-tables this is single thread process.

    case2 : if we use no.of dimensions -- Accessing of data is first hit fact table after different DIM-tables at a time from there SID-tables this is multi threaded process.

    Compare to case1 , case2 is more efficient.

    i think this Info help you.............

    Thanks & Regards,

    Mahesh.

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  • Posted on Dec 06, 2011 at 03:59 PM

    Hi

    We have to make sure that the size of the dimension table should be very less(probably it should be less than 20% of the size of the fact table) . suppose u have some 3 characteristic(say DOC_NUMBER etc..) and if that 3 characteristic generate more number of values so in that case SAP recommends to have more no. of dimension table so that the size of the dimension table will be less than 20% of the size of the fact table.

    u can get the size with the TCODE : DB02.

    Hope u got it,

    Assign points if it helps u ,

    Thanx & Regards,

    Ravichandra

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  • author's profile photo Former Member
    Former Member
    Posted on Dec 07, 2011 at 10:11 AM

    Hi,

    The technical reason for this is Oracle data base version (when cube designed in BW) one table can have max. of 16 Primary keys. So info cube we can have 16 dims. As data base wants to fetch the data from the tables Primary keys will play key role, If you more keys then where condition will act and will fast. Dims should be less than 20% of the size of the fact table, so that you will more primary keys and also you have to group the info objects logically in the dimensions.

    Thanks

    Riyez

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  • Posted on Dec 09, 2011 at 12:14 PM

    Hi,

    check following as well

    1.Reducing number of dim tables and

    2.Reducing no of records.

    1. If the Relation between the master data tables is 1:m or 1:1 then go for assigning single sid table to single dim table.

    2. If the relation in m:m then go for assigning multiple sid tables to single dim table.

    Performance:

    1. When u r designing a cube first think is there any requirement of report based on Calyear/month or fiscyearperiod. If there is any requirement then go for partitionong a cube.

    2. If u going to assign a single sid table to single dim table then go for making that dim table as "LINE ITEM DIMENSION TABLE"

    3. The size of dim table not greater than 20% of fact table.

    Check this........it will help you........

    so ratio is very important.If dimension and fact table ratio deviates then report will poorly perform while execution.

    Thanks and regards

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