what is technical advantage 0f having 16 dimension tablefor an fact table

[Former Member]

Hi ALL,

Clarify my doubt.

Regards

DEEPAK

[claudio_ciardelli2]

Gianfranco's answer is ot clear to me. Why are characteristics in a Dimension are limited to 248.

Someone once told me that this was related in some way to the maximum number of fields (256 fields?) that can exist in a Oracle database table (?). If that is true, how do you come up with 248 in the end.

I would gladly have the exact explanation to this...

Claudio Ciardelli

[Former Member]

deepak valluri :

I think that These rules was only made by sap according to some common dbms rules, so it is only a rule where there is not logic.

[Former Member]

May be when we have 13 unrelated chars to be modeled..

it looks me like a breakeven between Dim table rows and fact table lengths..

Just sharing my thoughts and little knowledge..

[Former Member]

Additional info if necessary:

16 is a technical limitation that comes from Oracle (related to the max nbr of fields of a primary key).

Regards,

LauQ

[Former Member]

hi laurent,

do you mean to say that the 16 dimension limit is something imposed by the underlying database?????

so does it differ if i install BIW on diferent database

and if ur answer is a yes ....then what about 248 characteristics per dimension.....where did this limitation arise from??????

[GFV]

Hi Sudhir,

the limit of 16 key fields comes from the underlying DB ... Most of them do not support more. There is no difference from this point of view using different DBs becauses SAP abstracts the underlying DB BUT does consider their "common" limits, so it's built considering that an ABAP table can't be formed with more than 1 key fields, because some DB don't support this requirement.

As far it concerns the consideration of 248 Chars per Dim ... in a Dimension table there is a surrogate DIMension ID (DIMID) as a key field! Characteristics are "attribute" fields. So this limitation hasn't the same cause.

Hope it's clear

GFV

[Former Member]

Thanks for your comments Gianfranco; I hadn't time to reply yet.

You're totally right!

Best regards.

LauQ

[former_member184494]

I would like to know what you mean by advantage. By having 16 dimensions ( 13+3 ) you would have a huge fact table and also you would have to deal with having related data in dimensions - in most cases you would run out of options beyond 5 dimensiona dna you could use more dimensions for reducing dimension table size but again it can also be done through line item dimensions.

Arun