Direct Query Row Limitations and Grouping

[stack23]

I read Direct Query has a limit of 1 million rows, but it can do rollups.

Say I do a Direct query on a SQL table

The Customertransaction table has more than 30 million rows.

I decide to only show productid (which only has values 1-4), and quantity sum in picture below. (not through query, but only by picking certain table columns). Will the PowerBI table do a full summation of all 30 million rows? The total row count is only 4, less than the million limit. 

create table dbo.customertransaction

( 

     customertransactionid int primary key,

     customerid int,

     productid int,

     quantity int

)

[AkhilAshok]

For the visual you showed, if your measure is just SUM([quantity]), Power BI DirectQuery will trigger an SQL:

SELECT productid, SUM(quantity)
FROM   dbo.customertransaction
GROUP  BY product id

It should be able to return the 4 rows without any issues, eventhough your fact table is 30m.

The 1million row limitation comes in to play mainly when you try some DAX functions, which PBI cannot translate into respective SQL function. In that case, PBI has not option, other than brining the entire dataset and compute the DAX function in memory.