Re: V$LATCH question

Jonathan Lewis doodled thusly:

PMFJI
>
>To decide if you need to tune the
>latches, (a) check v$system_event
>for the event 'latch free'. This is the
>amount of time lost in latch sleeps;
>if this is relatively high, then you may
>need to investigate latch contention.

This is interesting. I've had a few "fights" about exactly what constitutes "relatively high".

I'm currently looking after a db that gets approx 2500 latch free events every 24 hours, taking all of 18.7 secs in total during this period. Yet, one of the local "gurus" uses Toad to see this number going up during the heavy day processing and goes into a fit that the db is badly tuned, blah blah.

What can I say? :-)
What is relatively high? I'd think that if I had something like 1 hour of waits on this event, there would indeed be a problem. 18.7 secs in 24 hours? I'd look somewhere else for cause of problems, no?

>
>Note - however, that latch contention is
>usually a side-effect of another more
>important issue, such as unsuitable
>indexing, poor programming strategies
>etc.
>

Yup. How true.

Cheers
Nuno Souto
nsouto_at_optushome.com.au.nospam Received on Sat Dec 01 2001 - 06:11:44 CST