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Anonymous's avatar
Anonymous
Not applicable
4 years ago
Solved

Most efficient way to create reference tables from original table

Hi there,

 

I have a primary table in my PowerBI model, and want to perform several transformations to add custom columns.  

 

For example, my primary table contains a unique Customer ID per row, with a column for Parent ID.  For some rows, these two values will be the same, i.e. it's a Parent record, but for others they will differ, i.e. they are a child record.  Every individual row has a Last Booking Date.

 

I want to add a new column to my primary table which shows the most recent Last Booking Date for each differing Parent ID, so I have created a duplicate of my primary table, grouping on Parent ID and the MAX of Last Booking Date.

 

I've then merged this second table to the primary table, joining on Parent ID, and then expanded the columns for MAX Last Booking Date.

 

This achieves my goals, and I get the data I require in the new column, however I'm concerned that it might not be the most efficient mechanism to do so.

 

I've a number of similar scenarios I've run against my primary table, ending up with 3 duplicate tables - against which I've performed various types of data transformation.

 

It now takes quite a long time to refresh table previews, and I'm wondering if it's because each of the tables need to refresh in full to update my primary table.

 

Is there a more efficient way of achieving this type of manipulation, e.g. instead of duplicating the primary table, should I be referencing it?

 

Hope this makes sense anyway!

 

Thanks

Need Help
  • v-janeyg-msft's avatar
    v-janeyg-msft
    4 years ago

    Hi Anonymous 

     

    That's why I asked you to share sample data...Your previous sample is incomplete.

    Try this:

    Last Booking Date =
MAXX (
    FILTER (
        ALL ( table ),
        [Parent Cust ID] = SELECTEDVALUE ( table[Parent Cust ID] )
    ),
    [Booking Date]
)

      

    Best Regards,

    Community Support Team _Janey

    If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.

9 Replies

  • parry2k's avatar
    parry2k
    Icon for Super User rankSuper User
    4 years ago

    Anonymous Two ways to handle it:

     

    - if you want to use PQ, keep all transformations in one table and use it as a reference.

    - or best way is to use DAX measure, no additional tables will be required, just use one table with all the transformation and thru measure achieve the result. In the above example, just add a below measure and in table visual, put parent id and the measure, it should work

     

    Last Booking Date = MAX ( Table[Booking Date] )

     

     

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    • Anonymous's avatar
      Anonymous
      Not applicable
      4 years ago

      Perfect, thank you.  😁  DAX is a much better way of course! 🙄

       

      Ok, so next problem (sorry!).  I actually need to expose the MAX(Last Booking Date) across all Customer entities associated with the Parent Customer.  If I create a measure using Last Booking Date = MAX ( Table[Booking Date] ) then I get the Last Booking Date for the individual Customer in my report - which is at Customer Level.

       

      This is what I'm after, i.e. the Parent Last Booking date is the MAX of all Booking Dates associated with child Customer entities.

       

      Cust IDCust Last Booking DateParent Cust IDParent Last Booking Date
      123401/12/20999915/03/21
      456715/03/21999915/03/21

       

      Thanks! 

      • v-janeyg-msft's avatar
        v-janeyg-msft
        Icon for Community Support rankCommunity Support
        4 years ago

        Hi, Anonymous 

         

        So what should be the correct result?

        Can you share some sample data? So we can modify the code according to the field.

         

        Janey

  • Anonymous's avatar
    Anonymous
    Not applicable
    4 years ago

    Hi v-janeyg-msft ,

     

    Sorry, I'm not sure I understand.  The column you've highlghted in this sample table is the expected result.

     

    Both rows have the same Parent Cust ID, but differing Cust Last Booked Date.  The Parent Last Booking Date is displaying the MAX Cust Last Booking Date across all child entities.

     

    Naturally, this value will be repeated or all rows with the same Parent Cust ID, but this is not a problem.

     

    Hope that clarifies?

     

    C

      • Anonymous's avatar
        Anonymous
        Not applicable
        4 years ago

        Erm, not sure I understand.

         

        I do have a question...as described...

         

        "Ok, so next problem (sorry!).  I actually need to expose the MAX(Last Booking Date) across all Customer entities associated with the Parent Customer.  If I create a measure using Last Booking Date = MAX ( Table[Booking Date] ) then I get the Last Booking Date for the individual Customer in my report - which is at Customer Level."

         

        That table was jsut an example of the Parent Cust Last Booking Date column I'm hoping to create.