Re: how to place a table in memory

Richard Foote wrote:
> "Chuck" <skilover_nospam_at_softhome.net> wrote in message
> news:Xns95F970AD58DAskiloversofthomenet_at_130.133.1.4...
> > "David Aldridge" <slimdave_at_yahoo.com> wrote in
> > news:1108048751.524193.292820_at_f14g2000cwb.googlegroups.com:
> >
> >> I'd be interested in knowing why you want to do this -- my own
practice
> >> has just been to let the cache take care of itself, and I'm
suspicious
> >> that trying to pin a table in memory might actually be worse for
> >> overall system performance
> >>
> >
> >
> > If the table is small, and the optimizer determines it's faster to
access
> > it by a table scan, it will constantly be on the cold end of the
LRU list
> > be bumped from memory. Placing it on the keep pool will keep it in
memory,
> > reduce i/o, and improve performance of queries involving that
table.
> >
>
> Hi Chuck,
>
> If the table is actually "small" from Oracle's perspective (less than
2% of
> buffer cache or 20 odd blocks depending on which is greater), then
the table
> is assigned the CACHE characteristic regardless, meaning the table is
not
> constantly placed on the cold end of the LRU list (but joins the
partly 1/2
> way or so down the list)
>
> Then if the table is actually accessed constantly, it should be have
enough
> life left in the cache to be re-read from memory (although admittedly
with
> 8i/9i at least, the touch count algorithm is prejudiced against
cached
> tables)
>

Richard,

Can you please explain what 'constantly' is? Like once 15 seconds?

bdbafh (sorry, dont know your name), You said using buffer_pool_keep worked for you. What version of Oracle was that? Thanks all.

Thanks. Received on Fri Feb 11 2005 - 03:25:32 CST