Flash (Alert)
Abstract
You may have been faking the statistics information (e.g. cardinality) for nicknames to influence Optimizer to generate a specific plan. However, please note that, you might see that the plan generated by Optimizer gets changed when you enable the Automatic update of nickname statistics feature or migrate to Federation Server V9.5 with default setting. It in fact results in the fake statistics getting reset by the automatic feature.
Content
When the Automatic update of nickname statistics feature is enabled, the NNSTAT stored procedure will be run automatically, and set new values in statistics catalog tables. Since this feature is enabled by default in Federation Server V9.5, you may see it happens when migrating to this release. Please refer to Information Center for how to disable or customize this feature.
Related information
Information Center Documentation For Automatic update
Rate this page:
Copyright and trademark information
IBM, the IBM logo and ibm.com are trademarks of International Business Machines Corp., registered in many jurisdictions worldwide. Other product and service names might be trademarks of IBM or other companies. A current list of IBM trademarks is available on the Web at "Copyright and trademark information" at www.ibm.com/legal/copytrade.shtml.