Optimizing the PDX
A utility is available to optimize a PDX. BMC Software recommends that you optimize the PDX to improve performance. When a PDX is optimized, the directory is rewritten only when necessary. When a PDX is not optimized, the directory is rewritten each time a member is changed, even if the directory itself has not changed. Using an optimized PDX requires less I/O than using a PDX that has not been optimized.
The products can test an optimized PDX to determine when the directory needs to be rewritten, thus improving performance.
If you allocate or format a PDX using the March 1, 1995 (or later) level of the DBU code, the PDX will be optimized by default. Any PDX allocated or formatted before the March 1, 1995 level is not optimized.
Member DBUPDXOP of the sample library contains sample JCL to convert an existing PDX to optimized format (program DBUPDXV2).
To optimize an existing PDX, include the OPTIMIZE=YES parameter on the EXEC statement as shown in the following figure. If you do not include this parameter on the EXEC statement, the default is OPTIMIZE=NO (the PDX is not optimized).
//STEPLIB DD DSN=bmc.xxx.load,DISP=SHR <<==== CHANGE
//CONVPDX DD DSN=YOUR.PDXNAME,DISP=OLD <<==== CHANGE
//SYSPRINT DD SYSOUT=*
//
If you need to revert to a product level earlier than March 1, 1995, you must turn optimization off. You can use the sample JCL shown above to turn optimization off by specifying the OPTIMIZE=NO parameter on the EXEC statement.
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