IDMS: UNLOAD or REORG loop or take a long time

Products

• IDMS

Issue/Introduction

REORG or the UNLOAD process of the unload/reload utility appear to loop or just run for a very long time.

Environment

CA-IDMS: All supported releases.

Cause

There are records in the database being unloaded that are defined with the CALC location mode and allow DUPLICATES.

By default, REORG and the IDMS unload/reload process attempt to maintain the order of duplicates within a particular key value for CALC record types.

To do this, processing requirements increase in proportion to the square of the number of duplicates of a given value. In some cases, the difference can be extreme.

Resolution

Optional bit 93 should be considered.

It will greatly reduce the runtime of the unload at the expense of not maintaining the original order of duplicates.
What this means is that any code which processes duplicate CALC key values (using OBTAIN CALC and then OBTAIN DUPLICATE in a loop) may not read them in the same order after the REORG or unload/reload as it would have before.