ANALYZE option for estimating data set allocation in LOADPLUS

If you specify ANALYZE PAUSE or ANALYZE ONLY, LOADPLUS gathers information about the table space and the index space.

In addition to cardinality and average row size, the ANALYZE phase provides estimated data set sizes for the following data sets:

  • Load (SORTOUT)
  • Work (SYSUT1)
  • Sort work (SORTWK)
  • Discard (SYSDISC)
  • Error (SYSERR)
  • Image copy (BMCCPY, BMCCPZ, BMCRCY, and BMCRCZ)

Related topic

Building-the-LOADPLUS-job


Important

ANALYZE does not provide estimates for LOB or XML copy data sets. These data sets must be dynamically allocated.

LOADPLUS writes these statistics to SYSPRINT.

To use the ANALYZE function, you must also either enable automated file size estimation or specify an appropriate numeric value for the ENUMROWS command option.

ANALYZE PAUSE or ANALYZE ONLY provides the estimated information in table format. Messages BMC51530I, BMC51531I, and BMC51532I provide the heading information and multiple BMC51533I messages provide the estimates. LOADPLUS issues a separate BMC51533I message for each data set and provides the following information:

  • Data set name
  • Number of kilobytes
  • Primary and secondary 3380 cylinder quantities
  • Primary and secondary 3390 cylinder quantities
  • Index name, where applicable

Important

For rows that contain VARCHAR columns or tables that contain EDITPROCs, ANALYZE ONLY or ANALYZE PAUSE might report a secondary quantity for SORTOUT that is larger than the reported primary quantity because LOADPLUS bases the primary quantity on the average row length, and the secondary quantity on the maximum row length from the Db2 catalog. In this instance, we recommend that you provide a secondary quantity of approximately 25 percent of the primary quantity.

As an alternative to using ANALYZE to help you estimate sizes for data sets, you can have LOADPLUS dynamically allocate your data sets for you. To use dynamic allocation, you must

  • Either enable automated file size estimation (AUTOENUMROWS=ON or ENUMROWS AUTO) or specify an appropriate numeric value for the ENUMROWS command option.
  • Enable dynamic data set allocation, either in your installation options or with the DDTYPE command option.

For more information about dynamic allocation, see Dynamic-data-set-allocation and Dynamic-allocation-options.

If you do not use the PAUSE or ONLY keywords with ANALYZE, LOADPLUS also gathers the information described in this section. However, instead of pausing or stopping, LOADPLUS continues processing. If dynamic allocation is enabled, LOADPLUS uses the ANALYZE phase information to dynamically allocate your data sets. In this case, the ANALYZE phase does not write the statistics to SYSPRINT.

 

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