I have report running against large table , report gets data till I don't add group / overall summary, after adding summary to report , it does not get refreshed. Cognos changes report query for addition of summary function , is there a way to add group summary without changing the report query or any other best practice to deal with summary performance issue less...
			
			
			
				I would try the following:
 
    - Make a copy of the report
 - Discard the summary function
 - Copy the query
 - Change the second query to fetch the grouped item instead of the non-grouped one
 - {2nd query now has 2 dataitems on the grouped item}
 - Define a union using the 2 queries 
 - Build the list against the union 
 - Set the sort order on the dataitem that references the grouped item in both queries 
 - Compare performance between 2 reports