HALDB partition selection

IMS must select the correct HALDB partition whenever it accesses a database record. The selection process is called partition selection.

Partition selection determines the partitions in which the root segments are placed and the order in which partitions are processed.

IMS performs partition selection by using either key range partitioning, which is based on the high root keys of the partitions, or by using a partition selection exit routine, which uses selection criteria that you define.

IMS assigns database records to partitions based on the key of the root segment.

For batch, BMP, and JBP programs, a PCB can be restricted to access one or more partitions.