Re: latch free wait event

[Mogens N�rgaard]

"Can" instead of "Will" is probably only in the case where there's only 
one user on the system :-))).

Cary Millsap wrote:

Yes. Even with TIMED_STATISTICS=TRUE, relying on *any* statistic with
system-wide scope can waste your time. For a 34-page introduction to the
rationale behind this proposition, see:
        http://www.oreilly.com/catalog/optoraclep/chapter/ch01.pdf

Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com
Upcoming events:
- Hotsos Clinic 101 in Sydney
- Hotsos Symposium 2004, March 7-10 Dallas
- Visit www.hotsos.com for schedule details...
-----Original Message-----
Wolfgang Breitling
Sent: Thursday, September 04, 2003 6:44 PM
To: Multiple recipients of list ORACLE-L
The number of waits is irrelevant. What matters is the time waited which
in 
your case shows 0, but I assume that is because you have not set 
timed_statistics to true. Without that the data from v$system_event are 
worthless. Cary will probably step in here and tell you that even with 
timed_statistics that data is at best of dubious worth.

At 02:49 PM 9/4/2003 -0800, you wrote:

 

                               System-wide Wait Analysis
                                for current wait events
   

Average
 

Event                                 Total  Seconds        Total
   

Wait
 

Name                                Waits  Waiting     Timeouts  (in
   

secs)
 

-------------               ---------   ---------       ---------
-----------
latch free                            1,459        0         1,393
   

.000
 

After querying v$system_event my biggest concern is the "latch free"
   

wait
 

event. I understand that latch free is "the process waits for a latch
   

that
 

is currently busy ( held by another process).    How can I drill down
   

and
 

find the cause of this?   I have a feeling it is about rollback or redo
logs.
thanks,



David Ehresmann

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Wolfgang Breitling
Oracle7, 8, 8i, 9i OCP DBA
Centrex Consulting Corporation
http://www.centrexcc.com
 

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