Re: Cache buffer chains latch bug (8.1.7.2)

Hi,
even though I didn't read the origin of this thread I can add some of my own experience about this:
cache buffer chain latch contention may be due to lots of clones of the same block (because of consitent reads) in the buffer cache. This can happen for instance when there are many concurrent sessions doing full table scans or large index range scans using identical queries, like a webapplication accessing an oracle database that has many concurrent active sessions.
When this latch really becomes the bottleneck try to rewrite these expensive queries so they will access less blocks. Also reducing the buffer cache size or putting the tables and indices, of which there are many clones in the buffercache, in the KEEP bufferpool may help. Logical reads aren't always that cheap!

Andre van Winssen

"Andrew Mobbs" <andrewm_at_chiark.greenend.org.uk> wrote in message news:l0E*7grep_at_news.chiark.greenend.org.uk...
> Scott Gamble <zifnab_at_nospam.reddragon.org> wrote:
> >Oracle Version = 8.1.7.2.1
> >OS = Tru64 5.1 (might be 5.0 escapes me at the moment)
> >
> >Just wanted to keep those intersted in the cache buffer chains latch
> >bug that was present in 8.1.7.1 and 8.1.7.2 that I had posted about a
> >couple of times.
>
> Thanks for the update, I'm still very interested. I hope we see the same
> success (when I finally get a chance to try - the test has been pushed
> back a little).
>
> --
> Andrew Mobbs - http://www.chiark.greenend.org.uk/~andrewm/
Received on Wed Jan 16 2002 - 02:09:25 CST