Forum Discussion
Microsoft EmployeeDISTINCT over SUMMARIZE
- I do not see the need for DISTINCT, SUMMARIZE already makes things distinct.
Maybe, but don't know your data to be sure. Should just be able to use COUNTROWS and FILTER the table returned from SUMMARIZE but not sure that is more efficient or not.
Community Champion
No on DISTINCT with SUMMARIZE, because when you SUMMARIZE, whatever your are grouping on will be distinct. DISTINCT will make sure that entire rows are distinct in a table versus just a particular column, but the fact that you are using SUMMARIZE ensures that the table rows are distinct, it's built into the grouping.
Ashish_Mathur put into a formula what I was discussing with COUNTROWS and FILTER. Now, whether that is an improvment? You'd have to test it. See my 4 part series on Performance Tuning DAX: https://community.powerbi.com/t5/Community-Blog/Performance-Tuning-DAX-Part-1/ba-p/976275
Microsoft EmployeeAshish_Mathur and Greg_Deckler So I had three copies of the measures for which I tested the performance on my Power BI desktop. SUMX() was consistently better performing than COUNTROWS(FILTER() >0) pattern
And removing DISTINCT from SUMMARIZE also had some minor improvements on the run time. Maybe it would change in a huge dataset and the time difference would be considerable.
- Greg_DecklerThanks for the information! That does not surprise me, the "X" functions seem to be very performant overall, as I note in my To *Bleep* with RANKX Quick Measure, https://community.powerbi.com/t5/Quick-Measures-Gallery/To-Bleep-with-RANKX/td-p/1042520
v-xuding-msftCommunity Support
Hi karun_r ,
Thanks for sharing the results. And it seems that you have got the answer of the thread. Can you please accept the helpful answers as solutions? More people will benefit here.