3 Replies Latest reply: Feb 14, 2013 5:58 AM by Srini VEERAVALLI RSS

    Dimensional Modelling  issue

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