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It is recommended that you apply statistics to Siebel applications. The DBA should update statistics on table spaces that contain EIM interface tables and base tables (including table spaces that contain extension tables and repository tables) when there has been a change of 20 percent or more in the row distribution. It is usually not necessary to update statistics on all of the table spaces, only on those containing tables that have changed.
You should update statistics only when there is little activity on the system, such as after midnight. If you run this utility while users are accessing and updating the Siebel database, lock contention can occur. When this happens, an error message is generated. As an example, the following error message is generated from rstat390.
You should execute RUNSTATS following reorganization of any fragmented table spaces and indexes. For more information on this topic, see About Reorganizing Table Spaces, Partitions, and Indexes.
RUNSTATS collects distribution statistics, but only in certain cases: for example, only for columns which form the senior key of an index, and only for the most (rather than least) frequently occurring values.
A slow query may be a result of an inefficient access path chosen by the optimizer due to data skew on a non-leading indexed column. In such cases, IBM recommends running the DSTATS utility to collect column distribution statistics on such columns. Running DSTATS could significantly improve the query time. For example, on a query with search predicate
|Implementing Siebel eBusiness Applications on DB2 UDB for z/OS and OS/390|