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fact and dimension tables

Former Member
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hello all...using SAP_INFOCUBE_DESIGNS_PROGRAMME...i need to find the ratio of my fact and dimension table..

this is the result i got for my cube Z_T_CUBE..can anyone explain the values in the ratios shown and how to understand fact and dimension table size??

Accepted Solutions (1)

Accepted Solutions (1)

ravi_chandra3
Active Contributor
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HI

U can get the same by using the tcode DB02 plz follow the below link

http://www.sdn.sap.com/irj/scn/go/portal/prtroot/docs/library/uuid/d0427b8a-7fe5-2c10-f1be-a8be71fa2...

Regards,

RaviChandra

Former Member
0 Kudos

HI,

Generallly the Dimension to fact Table ratio should not ne more than 20% for better performance say like Data loading & Data Retrivel.

This infromation helps you to modify the Dimensions and see whether ratio is good or bad.

Accordingly you can set the properties of Dimension to either HIgh Cardinality & Line Item Dimensions.

This Improves the Performance of the cube.

For Doing this sort of performane tuning it is suggested to have good amount of records and see the ratio and then you will be able to judge what improements you can do.

Like if you are using less dimensions and one of the Diemension fact ratio is high , you may create another Dimension and move your objects to that new dimension. Even after doing so the ratio is high like 60 - 70 % you may mark the dimension as high Cardinal.

I have worked on some performance related actity on the cube and noticed the changes in our project. You  may get back to me if you need more information.

Regards,

Ganesh Thota

Former Member
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hi ganesh...

tanx for your reply..i actually want to know how is this 70% calculated??as shown in my image ter how did that 108% come..or how are they doing 14/13*100 inorder to det that 108%???

tanx

former_member210724
Contributor
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Hi,

It seems you are correct, in my system also it is like that.

Example: Dimension ratio = Dimension rows/Fact rows*100

Anand.

Former Member
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hi anand

but that 13 is taken a constand in all calculation in my image..also we know that the no of rows in dimension table should be less than 20% of fact table rows ..but in my bacic cube as u told no of dimension row is 14 and fact rows is 13...can u explain???

regards

kiran..

former_member186082
Active Contributor
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Hi Kiran,

As Anand said, the ratio (% in the last column) indicates the number of rows in that  table divided by number of rows in the fact table.

In your cube, the number of rows in fact table are 13. Hence the denominator remains 13 for all the calculations. This is the reason, for the fact table (last row) resulted 100%

Rows in that table = 13

Rows in fact table = 13

Dimension ratio = (Rows in that table / Rows in fact table)* 100 = (13/13)* 100 = 100%

As per SAP standard, the ratio of fact table rows to dimension table rows should not be more than 10%. Whenever this ratio crosses, the row will be highlighted in red color, thereby we should go redesigning that dimension. The highlighting of rows will be activated only if the cube has 30,000 rows

Please look into note 1461926 for better understanding on this report


Regards

Chandu

Former Member
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hi chandra

so as the no of rows in 1 of my dimension table(14) is greater than my fact table rows(13)..u mean that i shoud consider redesigning my cube????

regards

kiran

former_member186082
Active Contributor
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Hi Kiran,

As per dimension ratio, yes. But as the number of records are very less, it is not required to redesign. As I said, the ratios greater than 10% will be highlighted in RED and we have to redesign them. But this will happen only if cube has 30000 rows. Hence in your case, this can be ignored and is not required to redesign that dimension

Regards

Chandu

Former Member
0 Kudos

Hi chanrda

thanku verymuch....

regards

kiran

Answers (0)