Re: Queries which causes log file sync
- From: Tanel Poder <tanel@xxxxxxxxxx>
- To: Marcin Przepiorowski <pioro1@xxxxxxxxx>
- Date: Fri, 15 Oct 2010 18:13:41 +0300
>
> > Note that the memory structure underlying the obj# printout is populated
> by
> > things like IO waits, some enqueue waits (I think) and buffer busy waits
> > etc. However, these values aren't cleared, so whatever is the next wait
> > event (which doesn't overwrite the obj#) - it may just report some old
> > wait's obj#...
>
> BTW
>
> This same issue appear to exist in v$session tables when session is
> going from waiting to on cpu state - it looks like latest wait event
> is not cleared as well - sometimes can be useful but can also do some
> unnecessary mess.
>
>
Yep, it's because SQL trace picks this stuff from v$session array... For
example when you have cache buffers chains latch contention, then you can't
trust the obj# nor the file#,block# numbers either (not in v$sesstat, not in
SQL trace) as latch wait events just don't update this information....
Tanel
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