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DB2 RUNSTATS may be slow due to UTIL_IMPACT_PRIORITY option

Technical Blog Post


Abstract

DB2 RUNSTATS may be slow due to UTIL_IMPACT_PRIORITY option

Body

RUNSTATS has an option UTIL_IMPACT_PRIORITY which as its name suggests, specifies the priority of RUNSTATS utility.

 

However, be aware of the following implications

Option Specified  RUNSTATS Priority
Option UTIL_IMPACT_PRIORITY not specified  Unthrottled
Option UTIL_IMPACT_PRIORITY used, no value specified Throttled, Priority is 50 (Default)
Option UTIL_IMPACT_PRIORITY used, value 1 to 100 specified Throttled, Priority is 1 to 100 as specified

:

When RUNSTATS is throttled, the overall performance impact is controlled by UTIL_IMPACT_LIM:

The DBM config parameter limits the performance degradation of a throttled utility on the workload and

it has 10% as default impact value.

The above means, even if you specify UTIL_IMPACT_PRIORITY 100 with RUNSTATS, it may still

run slow because the overall utility(which includes RUNSTATS) impact is limited to 10%.

 

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ibm11140442