"Count Distinct Row" operation in Group By does not Query Fold?

[BSLATTER]

Hi all,

I have a directquery Query on "MySalesTable" where I run a few filtering operations and it query folds fine. I then reference it and perform group bys to create "Imported" aggregate tables. So far so good.

However when I attempt to create an aggregated table based on the distinct number of invoices in my Sales data - It does not seem to utilize query folding (and thus does not complete in any kind of reasonable timeframe)

Here is the M code for my imported table:

let
Source = MySalesTable, 
#"Removed Other Columns" = Table.SelectColumns(Source,{"DIM_A_KEY", "DIM_B_KEY", "DIM_C_KEY", "INVOICEID"}),
#"Grouped Rows" = Table.Group(#"Removed Other Columns", {"DIM_A_KEY", "DIM_B_KEY", "DIM_C_KEY"}, {{"InvoiceCount", each Table.RowCount(Table.Distinct(_)), Int64.Type}})
in
#"Grouped Rows"

Any ideas why this won't query fold?

[amitchandak · Accepted solution]

@BSLATTER , refer if this can help https://www.youtube.com/watch?v=75LHPS3lOFg

[BSLATTER]

Thank you for that link - yes my problem was thinking "Count Distinct Rows" operation should query fold, whereas you actually have to "Remove Duplicates" and then "Count Rows" operation to maintain the query folding.

An odd issue - but this helped me resolve my situation. Thanks again!