Re: statistics_level=ALL slows query 10x.

As Greg pointed out, it's almost always a good idea to set statistics_level only at session level for the session that needs it. If you can't inject "alter session" into a session, consider a logon trigger.

You may only need the extended plan statistics for SQL tuning purposes, not everything else implicitly enabled by setting statistics_level to all. (Most of those "side effects" of setting it to all are shown in part II and appendix II of
http://yong321.freeshell.org/computer/ParameterDependencyAndStatistics.doc)

I don't know how to explain why setting statistics_level to all eliminates recursive calls. Is it reproducible, with mixed order of setting the parameter to typical and all?

Yong Huang

> I have a database that when statistics_level=ALL is set, queries become
> 10x slower, spending all their time on CPU. I have run 10046 trace and
...
> When statistics_level=ALL it show no recursive sql and all CPU time.
...
> What is the next thing to trace to find out where the time is being spent
> when statistics_level=ALL?

--
http://www.freelists.org/webpage/oracle-l