What optimizer thinks about your statistics – SYSSTATFEEDBACK
DB2 optimizer relies on statistics about tables and indexes. In most cases, if optimizer could
exploit more complete and accurate statistics, queries would perform better.
While, DB2 users often only gather standard or default statistics. It’s a challenge for users to identify
what detailed statistics should be gathered for the specific queries. This is a main reason for sub-optimal
(unsatisfied) query performance.
Start from V11, DB2 optimizer provide recommendations for missing/conflicting statistics via a new catalog table.
With it, DB2 users can easily gather accurate and complete statistics for optimizer and result in better query performance.
Yet, this practical new enhancement has not been widely utilized by DB2 users.
In this session, we will explain how DB2 worked in V11/V12, demonstrate how to utilize and benefit from it.