Power BI Time Adventures
A customer reported that a Power BI date filter/slicer set to a specific date in Date dimension, let’s say April 24, 2020, doesn’t return some rows from the fact table that match that date. Upon some digging, the data was imported from Dynamics CRM and the source date column had UTC time. Power Query showed Date/Time/Timezone as a data type. However, the developer has converted the corresponding field in the model to the Power BI Date data type to remove the time portion. And indeed, the Data View would show that date as April 24, 2020 (without the time portion). So, why no match?
The xVelocity storage engine (the storage engine behind Power BI and Analysis Services Tabular) has only one data type for dates: DateTime. If you convert the field in the data model to Date, it still keeps the time portion (UTC or not) and it doesn’t change the column storage. It just changes to the column formatting to show the date only.
To get rid off the time portion, cast to Date in the data source (e.g. in a wrapper SQL view) or change the data type of the column in Power Query to Date. This will “remove” the time portion. In reality, xVelicity will convert the time to midnight.
