**  Dummy code; 
data input ;                                                                                    
   do k1 = 1e6 to 1 by -1 ;                                                                     
      k2 = put (k1, z7.) ;                                                                      
      do num = 1 to ceil (ranuni(1) * 6) ;                                                      
         output ;                                                                               
      end ;                                                                                     
   end ;                                                                                        
run ;                                                                                           
 
**  Standard approach using Proc Summary;  
proc summary data = input nway ;                                                                
   class k1 k2 ;                                                                                
   var num ;                                                                                    
   output out = summ_sum (drop = _:) sum = sum ;                                                
run ;                                          
 
**  Alternative using the hash object;
data _null_ ;                                                                                   
   if 0 then set input ;                                                                        
 
   dcl hash hh (hashexp:16) ;                                                                   
   hh.definekey  ('k1', 'k2'       ) ;                                                          
   hh.definedata ('k1', 'k2', 'sum') ;                                                          
   hh.definedone () ;                                                                           
   do until (eof) ;                                                                             
      set input end = eof ;                                                                     
      if hh.find () ne 0 then sum = 0 ;                                                         
      sum ++ num ;                                                                              
      hh.replace () ;                                                                           
   end ;
   rc = hh.output (dataset: 'hash_sum') ;                                                       
run ;