HD Sort utility

The HD Sort utility is a functional alternative to the IMS System Utilities/Database Tools HDAM Physical Sequence Sort/Reload utility (PSSR). The HD Sort utility does not completely replace PSSR. This section provides an overview of the HD Sort utility.

You must invoke the HD Sort utility (before or during the RELOAD job step) when you perform any of the following tasks:

• Change the key of a root segment
• Convert an HDAM database to HIDAM or HISAM
• Convert a PHDAM database to PHIDAM
• Convert a HIDAM or HISAM database to HDAM
• Convert a PHIDAM database to PHDAM
• Change the randomizer parameters for an HDAM or PHDAM database (except maximum insert bytes)

To model proposed changes to an HDAM or PHDAM randomizer, use the HDAM Randomizer Analysis utility of POINTER CHECKER PLUS.

PSSR is designed to prevent cascading when you reload a database with the IMS Reorganization Reload utility. The HD Sort utility is designed to take advantage of the Reload function’s technique for preventing cascading (the SCAN option).

The following figure shows where the HD Sort utility step fits within a simplified database reorganization process. Before and after the reorganization, take an image copy of the database and check the pointers. If the reorganized database has logical relationships or secondary indexes, you must run jobs to process these elements.

The HD Sort utility step normally runs after the DBDGEN that creates the new DBD and before the reload step. The Reload function performs the sort during the reload step when you include the HDSORT(YES) keyword on the RELOAD command. If you specify HDSORT(AUTO) on the RELOAD command, the Reload function determines whether the HD Sort utility or the RAP Sequencer is needed. The Reload function uses the method that is most efficient for the database. If you require the standard HD Sort utility, specify HDSORT(YES); otherwise, you can run the HD Sort utility as a stand-alone utility and specify HDSORT(NO) at reload time.

The HD Sort utility sorts an HD Unload data set. The HD Sort utility does not run in a full IMS environment; it uses only the information included in the DBD. Therefore, if you are using a customized randomizer that expects register 7 to contain the process scheduling table (PST) address, register 7 will not be initialized because it requires a full IMS environment. When the randomizing routine gets control, registers 0 and 7 point to dummy blocks instead of IMS control blocks. The HD Sort utility uses registers 1, 9, 13, 14, and 15 in the same way IMS uses them.

If VLSHRT(YES) is the DFSORT installation default specification, you must include a DFSPARM DD statement to override this default. For details, see JCL-requirements-for-the-HD-Sort-utility.

This section contains the following topics: