Am facing a strange situation. We were trying to improve performance for some query. On doing some query modifications; PROCSU in DSN_STATMNT_TABLE did reduce from 4 to 1. But when I run the jobs using these queries with the same volume of input file records; CPU time is almost same. Does the change in PROCSU reflects somewhere else and not CPU time? Then how the performance would impact. Please share your thoughts.
Joined: 03 Sep 2010 Posts: 3 Location: CHENNAI, INDIA
DB2 EXPLAIN is dynamic in nature. PROCSU is more like a hint provided by optimizer on how much service units (read as resource) a query "might" consume. When you bind your package and execute the actual query optimizer may take a more informed decision depending upon various factors. It is always better to use EXPLAIN PROCSU as an estimate.