Calculate the size for SYSIDMS parameter SORTSIZE_ESTIMATE when running IDMSDBAN

Products

• IDMS
• IDMS - Database

Issue/Introduction

By default, IDMSDBAN passes to the SORT a value of 999999999 records. For smaller databases this value is much larger than is required and leads to inefficient use of the sort work space. For larger databases 999999999 may not be enough.

The  SYSIDMS SORTSIZE_ESTIMATE parameter was introduced by PTF RO76079 for 18.0, RO73561 for 18.5 and RO79159 for 19.0 and provides the ability to specify a more suitable value. Also with PTF RO97151 for 19.0 and RO97147 for 18.5, it can be as long as 12 digits.

How to calculate the size for the SYSIDMS parameter SORTSIZE_ESTIMATE?

Environment

Release: All supported releases.

Resolution

There is no formula to calculate this value.

With IBM and other SORT packages, messages are issued to indicate the number of records read. Use these sort statistics from previous runs to set the SORTSIZE_ESTIMATE value for future runs. 

For small  databases, start with a smaller number for SORTSIZE_ESTIMATE than 999999999 and then compare to the number of sort records read. If lower than the sort records read, then increase the value. 

For large databases, start with a number larger than 999999999 and then compare to the number of sort records read. If lower than the sort records read then increase the value.