Memory intensive measure optimization

[gp10]

Hi community,

I have a table with over a billion of rows. In that table I want to run a measure on the column with the largest cardinality (col1) grouped by a column with lower cardinality (col2).

The measue is like:

Avg Unique Col1 IDs per Col2 IDs =
AVERAGEX ( VALUES ( Table[Col2 ID]), DISTINCTCOUNT(Table[Col1 ID]))

When my entire data range is selected this measure returns an error with the message:

Resources Exceeded

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More details: consumed memory 13154 MB, memory limit 10240 MB

Can we optimize this measure for better performance?

Thanks.