Babu & list,
If we are referring to the "free memory" statistic
from v$sgastat, the closer that number is to 0, the
better. If you see a very large number, it indicates
an "overallocation problem" in one or more components
of the shared/large/java pools.
And without getting on the soapbox, there is NO such
thing as an "healthy cache hit ratio". There is only
one thing that is relevant to any Oracle system and it
is "wait events". I have seen 99.98% systems crawl
like snails and 56% systems fly through like grease
lightning.
Moral of the story - Don't worry what your cache hit
ratios are, look at your wait events, go after your
system's bottlenecks, proactively manage the memory
allocation of various components of your SGA and your
PGA, encourage cursor sharing, reduce hard parsing,
reduce soft parsing, encourage "caching session
cursors" and for everyone's health fix those SQL
statements where the whole thing begins.
Cheers,
Gaja
- orclbabu <orclbabu_at_hotmail.com> wrote:
> Seema
>
> the answer is "it depends"... you need tyo have
> enough space in your sga to
> maintain a healthy hit ratio.
>
> how high is healthy depends on the nature of
> application.
>
> Babu
> ----- Original Message -----
> To: "Multiple recipients of list ORACLE-L"
> <ORACLE-L_at_fatcity.com>
> Sent: Wednesday, July 11, 2001 1:32 PM
>
>
> > Hi
> > How much percentage SGA should be free for OLTP
> application?
> > Thanks in advanvce.
> > -Seema
> >
>
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Gaja Krishna Vaidyanatha
Director, Storage Management Products,
Quest Software, Inc.
Co-author - Oracle Performance Tuning 101
http://www.osborne.com/database_erp/0072131454/0072131454.shtml
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Received on Wed Jul 11 2001 - 23:00:32 CDT
