ILDS reorganization updates

The HD Reorganization Reload utility updates the ILDS for partitions that contain targets of logical relationships or secondary indexes.

The utility has three options for updating an ILDS after a reorganization:
  • No control statement
  • ILDSINGLE control statement
  • NOILDS control statement

If you do not specify a control statement in the SYSIN data for the HD Reorganization Reload utility, an ILDS entry is updated or created when a target of a secondary index or logical relationship is inserted in the partition. An entry exists if a previous reorganization loaded the target segment in the partition. The updates to the ILDS are done in VSAM update mode. When a CI or CA is filled, it must be split by VSAM. Free space in the ILDS can help avoid these splits. Updates can be random or sequential. This depends on the order in which these segments are inserted and their ILKs. The ILDS keys are based on the ILK that is based on the location of the target segment when it was created.

You can create free space in the ILDS by specifying the ILDSINGLE control statement. The ILDSINGLE option provides a number of performance benefits, including eliminating CI and CA splits, eliminating unused ILEs, and better performance for subsequent reorganizations and recoveries. The ILDS must be deleted and redefined prior to running the utility with the ILDSINGLE option.

If you specify the NOILDS control statement in the SYSIN data, the HD Reorganization Reload utility does not update or create entries in the ILDSs. You must rebuild the ILDS by using some other means, such as the HALDB Index/ILDS Rebuild utility (DFSPREC0).

Using the NOILDS control statement provides the fastest reload, and the HALDB Index/ILDS Rebuild utility can update the ILDS for each partition in parallel; however, the HALDB Index/ILDS Rebuild utility reads each partition to update its ILDS. Optionally, the HALDB Index/ILDS Rebuild utility can rebuild the ILDS in VSAM load mode, which can improve performance and includes free space in the ILDS.

The HD Reorganization Reload utility also has an ILDSMULTI control statement; however, ILDSMULTI applies only to migration reloads. For more information about ILDSMULTI, see the HD Reorganization Reload utility section of IMS Version 15.2 Database Utilities.