Unlike the standard COLLECT STATISTICS statement, COLLECT STATISTICS (QCD Form) does not write the statistics it collects into the data dictionary for use by the Optimizer. The COLLECT STATISTICS (QCD Form) writes its statistics into the TableStatistics table of the specified QCD database, where the information is used by various database query analysis tools to perform index analysis and validation.
Because COLLECT STATISTICS (QCD Form) does not write its statistics to the data dictionary, it does not place locks on dictionary tables. Through appropriate control of the sample size, you can collect sample statistics for index analysis during production hours without a noticeable negative effect on system performance.