VIDEO: Data Model Development Best Practices In Power BI

I watched the above video today and was shocked with what you showed. I have been investigating Power BI for about 3 years and everywhere I go, it is suggested that a STAR SCHEMA be used. This obviously requires upfront study to determine the fact table and dimensions to be populated. The video today showed a schema straight from the transaction system—not a best practice.

I do not even know where to start with my questons — but I have lost a lot of confidence today in Enterprise DNA.

A friend showed me her companies PBI model and it was exactly as shown in your video - not a STAR. This makes everything in the model more confusing.

???
Confused
Wally

@Wally ,

I watched the video today too, and would be very interested to hear ways in which you think @sam.mckay 's model violated a star schema approach? Star schema is not limited to a single fact table, but characterized by fact tables filtered by a single level of dimension tables (as opposed to a snowflake schema with multilevel dimension tables) and connected to the fact table(s) (and NOT to each other) via key fields in a unidirectional one-to-many relationship at the appropriate level of granularity. I saw no violations of any of that in Sam’s model, so I’m not sure where your “loss of confidence” comes from.

I would suggest perhaps reviewing the definition and characteristics of a star schema:

– Brian

2 Likes

Hi @Wally.

I watched the replay of the video this morning, and I’ll echo @BrianJ’s comments; @sam.mckay did use a data modelling approach consistent with the eDNA teachings - a standard waterfall layout, albeit looking more complicated this time as there were multiple fact tables instead of just one.

The model has:

  • multiple (shared) lookup tables on the top row
  • multiple (6) fact tables (Lap Times, Qualifying, Results, Constructor Results, Driver Standings, Pit Stops) below

I’ve consumed hundreds (more likely thousands, actually) of eDNA videos and always found a clear, consistent approach to data modelling. I as well would be interested in hearing from you what you think the violations were.

Greg

2 Likes

I echo what @Greg and @BrianJ has commented. I turned into the actual live webinar and followed along what Sam was instructing us on a data set that he never has used before.

Thanks
Keith

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