334 HA Architectures & Capacity Planning with WebSphere Remote Server V6
faster. For better optimization, it is now also possible to update the statistic of
temporary tables with the runstats command.
11.2.7 Maintenance
Performance tuning is a constant task. An administrator can do maintenance
tasks regularly to keep good performance.
Runstats
DB2 UDB has an optimizer that looks for the best way to retrieve data. The
optimizer uses statistical data to calculate the lowest price for retrieval. With the
runstats command, the statistical data is collected and stored in the catalog.
The optimizer knows, for example, how many rows a table has and can
determine if an index scan is useful or to just use a table scan.
The statistic data must be updated ...