Advice for UDF used in GROUP BY

[Yiannis Gkoufas]

Hi there,

I was just looking for some tips on implementing a UDF to be used in a
GROUP BY statement.
For instance lets say I have the table:

( (A, B), C, D) with (A,B) being the composite key

My UDF targets the field C and I want to optimize the query:

SELECT A,MYFUNCTION(C),SUM(D) FROM MYTABLE GROUP BY A,MYFUNCTION(D)

Thanks a lot!