Sequential dependent segment storage

DEDB sequential dependent (SDEP) segments are stored in the sequential dependent part of an area in the order of entry.

SDEP segments chained from different roots in an area are intermixed in the sequential part of an area without regard to which roots are their parents. SDEP segments are specifically designed for fast insert capability. However, online retrieval is not as efficient because increased input operations can result.

If all SDEP dependents were chained from a single root segment, processing with Get Next in Parent calls would result in a backward sequential order. (Some applications are able to use this method.) Normally, SDEP segments are retrieved sequentially only by using the DEDB Sequential Dependent Scan utility (DBFUMSC0), described in IMS Version 15.5 Database Utilities. SDEP segments are then processed by offline jobs.

SDEP segments are used for data collection, journaling, and auditing applications.