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Don Burleson Blog 







Oracle timed_statistics tips

Oracle Database Tips by Donald BurlesonApril 26,  2015

As a prerequisite for bottleneck or wait-based analysis, it is imperative that the timed_statistics initialization parameter be set to TRUE, if the Oracle wait events are to be examined in detail. 

In early releases, the default for timed_statistics was FALSE, which disallows the collection of wait times for each wait event defined in the Oracle engine. 

In later releases, if statistics_level is set to TYPICAL or ALL, then timed_statistics=true.  Conversely, if statistics_level is set to BASIC, then timed_statistics=false.

The overhead of timed_statistics is negligible, and we recommend that timed_statistics always be set to true.

Starting with release, the value of the timed_statistics parameter cannot be set to false if the value of statistics_level is set to typical or all.

In order to make the trace files more useful the DBA should also set the parameter TIMED_STATISTICS to TRUE.

As long as a user has ALTER SESSION permission they can alter their own session to be traced. The following commands will turn on tracing in a user session:


In Oracle 9i and beyond, the DBMS_SYSTEM.SET_INT_PARAM_IN_SESSION package can be used to alter the settings of session alterable parameters.



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