Improving performance using internal expression processing

For simple criteria, Z Data Tools can process the expression internally without needing to invoke REXX. This can result in faster processing of record identification and record selection criteria. If an expression is not eligible for internal processing, Z Data Tools displays the message “REXX required” when you press Enter on the relevant panel. In this case, you can choose to either modify the expression so that REXX is not required, or use the expression with REXX processing instead of internal processing.

For an expression to be eligible for internal processing, it must consist only of:

These rules also apply when creating conditions in an IF-THEN-ELSE statement within a FASTREXX procedure.

Related concepts