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3 Replies Latest reply: Feb 14, 2013 3:58 AM by Srini VEERAVALLI RSS

Dimensional Modelling  issue

955015 Newbie
Currently Being Moderated
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 ?

Please share your valuable suggestions..


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
    955015 Newbie
    Currently Being Moderated
    Is this a right forum to ask dimensional Modelling doubts?
    If no, please tell me the valid one
  • 2. Re: Dimensional Modelling  issue
    Dhar Expert
    Currently Being Moderated
    Hi,

    To answer your questions

    [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
    Srini VEERAVALLI Guru
    Currently Being Moderated
    For your questions:
    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

    Let me know if need more info.

    If helps mark

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