SQL Optimizer for DB2 LUW 4.3.1 - Release Notes

What Function Should l Use to Retrieve the Run Time?

The SQL Optimizer provides two different measurements of performance; the run time for retrieving all records and the run time for retrieving the first n records. Both measurements give you an indication on the fastest running SQL statement—but with two different aims. You must understand the use of the SQL statement in the application. Generally, if the SQL statement is used for reports, then you should use the Run for All Record or Batch Run with Run Time Mode set to All Records. If the SQL statement is used for online query, then use the Run for First Record or Batch Run with Run Time Mode set to First n Record.

Note: If the aim of the SQL statement is unknown, then use All Records as a performance indication.