The data profiling tools look at the first 1,000 rows in the preview data loaded an shows you the big picture of what the data “looks” like.
Currently the profiling tool only works on the top 1000 rows of data. It also takes some time to prepare the profile of the columns (as could be expected), however the benefits of getting this stuff right before moving on far outweigh the slower load times (IMO). I would love to see an option to profile the entire set of data for one or more columns. I am sure this will come.
That’s all data profiling you get for now. Here is what it will take to make Power BI data profiling a killer feature:
Allow data profiling over all the values (understandably there will be performance impact).
Add more aggregates, such as Min/Max/Std/Median.
The ability to dynamically filter the preview data for the selected bar in the profile.
As it is, there’s enough here to see the potential of where it could go.