3 Replies Latest reply on Feb 14, 2013 11:58 AM by SriniVEERAVALLI

# Dimensional Modelling  issue

Hi,

I am working with Stock Exchange data, as per the availability of data, I found 2 dimensions that is
*(1)Time*
*(2)Company*

In my fact table, some of the fact(measures) are changing based on Date(Day) and some of the them are changing based on Time

My questions:
[1] : Can a dimension model have only 2 dimensions ?
[2] : Can I make 2 fact tables, Fact-1 will store measures based on the Date(Day) and Fact-2 will store measures based on the Time ?

Thanks.

Edited by: 952012 on Feb 14, 2013 1:19 AM

Edited by: 952012 on Feb 14, 2013 1:51 AM
• ###### 1. Re: Dimensional Modelling  issue
Is this a right forum to ask dimensional Modelling doubts?
If no, please tell me the valid one
• ###### 2. Re: Dimensional Modelling  issue
Hi,

[1] : Can a dimension model have only 2 dimensions ?

Yes, A dimensional model can work with just one dimension.

[2] : Can I make 2 fact tables, Fact-1 will store measures based on the Date(Day) and Fact-2 will store measures based on the Time ?

Going by the principles of modeling, no two facts with different grains should be merged. So, in case your Day & Time are different levels, then yes, make two fact tables at these levels.

Hope this helps.

Thank you,
Dhar
• ###### 3. Re: Dimensional Modelling  issue
1->Yes, there is no restrictions. Make sure a dimension is joined to any other object. It can be self join using Alias.
2->Creat a logical fact able in BMM and add DayFact and TimeFact as logical sources and set proper content levels if needed.

Since you are going with 2 different granularity, for time you might need a new dimension table as good as W_DAY_D interms minutes.
I think you might need it for analysis based on time and this also helps you to roll up to the day level.
Generally 20130214 is surrogate key for w_day_d for today's record, similarly for Time level you have to go for each minute like
1-->00:01 AM
2
3
....
60-->01:00AM
101-->01:01AM
.... like that to cover 23:59 PM