Re: db_block_lru_latches

It would nice for you to bound your statements Gentlemen as in "At least with Oracle8.1.x.x on such and such an OS I have found that using greater than x db_block_buffers..." you make it sound like all versions of Oracle are affected by these problems.

At my current client we are using 400,000 16K buffers and have not seen the problems you are stating on 8.1.7.3 64bit on HP. In fact, we are using all buffers most of the time and have not seen any of the buffer problems you describe.

Mike Ault

"Jonathan Lewis" <jonathan_at_jlcomp.demon.co.uk> wrote in message news:<1028878742.7095.0.nnrp-01.9e984b29_at_news.demon.co.uk>...
> There is at least one problem that can appear if you
> set db_block_buffers too large - redundant buffers seem
> to allow Oracle to breach the _max_cr_dba_block
> limit in high-speed OLTP systems. This can result
> in very long chains of CR blocks for critical blocks,
> which results in the associated CBC latch being
> held for a long time and causing silly amounts of
> contention.
>
> --
> Jonathan Lewis
> http://www.jlcomp.demon.co.uk
>
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> Nuno Souto wrote in message ...
> >
> >>The value of db_block_buffers is
> >> 100,000.
> >
> >Yikes! Unless you're running some third party app with a weird behaviour,
> >that's way too high. I've found 20000 seems to be the sweet spot for
> >most apps nowadays. And I find it's more influenced by the nature of the
> app
> >and the number of concurrent users than by size of db.
> >Of course the "SAPeans" here will disagree with me and allocate at least
> >8 Gb of buffers. Then again, who cares? Mem is cheap, never mind if you
> >never use it... ;-)
> >
Received on Fri Aug 09 2002 - 13:23:32 CDT