if you using cost based optimizer then you should collect stats.. I think...over a period earlier stats can be purged thanks....subodh On 17 February 2011 01:26, dba1 mcc <mccdba1@xxxxxxxxx> wrote: > I saw a ORACLE document "Performance Tuning Guide for Siebel CRM > Application on Oracle Part I - Cost-Based Optimization Guide" On this > article it say "don't analyze system statistics": > > ================================================== > System Optimizer Statistics > In 9i, Oracle introduced cpu_costing, a mechanism that allows the CPU cost > of an operation to be included as part of the overall estimate. This feature > is enabled in 9i only if you collect system statistics. This feature in 10g > is enabled by default. Oracle Database 10g gathers two types of system > statistics - statistics captured without a workload (noworkload) and > statistics captured with a workload. In addition to CPU cost, disk I/O and > memory utilization are also captured, to ensure that CBO picks the plan with > the lowest estimated cost relative to other plans. > Many Oracle DBAs attempt to leverage system optimizer statistics for > further tuning of Siebel CRM application. Such actions may cause > unpredictable degradation in performance of certain Siebel CRM application > views and queries, and are strongly discouraged. We recommend that DBAs > refrain from collecting system optimizer statistics, or altering any Oracle > default settings pertaining to systems statistics. > > ============================================================ > > I also see another ORACLE document say you need "analyze system statistics" > to avoid stange thing happen. > > Can Anyone tell me should I or Should NOT 'analyze system statistics"? > Thanks. > > > > > -- > //www.freelists.org/webpage/oracle-l > > > -- ============================== DO NOT FORGET TO SMILE TODAY ==============================