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Re: Max SGA size in 32 bit Oracle

From: kipnukpup <kipnukpup_at_netscape.net>
Date: Wed, 21 Feb 2001 22:34:26 -0800
Message-ID: <3A94B2F2.F345587@netscape.net>

Sybrand, I fully understand what you are talking about. We have a new version of an in-house application coming out, and the requirements are for a couple three rather large tables to be kept in memory, thus the larger SGA requirements (currently we have about 150MB SGA for this app). It doesn't have anything to do right now with the hit ratios.

Thanks, and yes luckily our engineers and developers are well trained and use bind variables. :-))

Sybrand Bakker wrote:

> Just a few general remarks.
>
> As explained before increasing indiscriminately the SGA has it's
> tradeoffs. In many cases you will just create a different problem
> area.
> Also: to gain that last 1 or 2 percent more, you need much much more
> resources. You always should consider whether you really need that
> Finally: If your application is firing 'random' sql, without using
> bind variables (in my experience: *all* jdbc applications) you can
> increase the sga and especially the shared pool what you want, but the
> hit ratio will remain at what it is: way too low.
>
> Hth,
>
> Sybrand Bakker, Oracle DBA
>
> On 22 Feb 2001 05:21:04 GMT, xux_at_informa.bio.caltech.edu (Xuequn Xu)
> wrote:
>
> >GC, does the same application run faster in 64-bit oracle than in 32-bit version?
> >I wonder whether larger SGA can buy you improved performance or not... In my
> >understanding, the same application will probably not speed up in 64-bit; what
> >the huge SGA buys you is the larger number of concurrent connections (i.e. allowing
> >more tasks to be done, but each task may not necessarily run faster than it
> >would in 32-bit oracle). Is this true? Thanks.
> >
> >GC (assistant_madman_at_hotmail.com) wrote:
> >: kipnukdog wrote:
> >: >
> >: > Sybrand, thanks.
> >: > I understand the guidelines, but is it possible, say on a 16GB Memory machine
> >: > would you be able to allocate more than 2.5 GB to the SGA? (we have some very
> >: > large buffer_pool_keep requirements) I have read on a 32 bit Oracle
> >: > installation, 1.74GB is max, unless you remap the SGA in the kernel, and then
> >: > you are allowed up to 2.5GB.
 

> >: If you are running 64-bit, then yes, you can have a larger SGA than
> >: 2.5GB (we have a db with about 8GB sga).
> >: If it's 32-bit, then no, you are stuck with the 2.5GB limitation.
 

> >: Cheers,
> >: GC
Received on Thu Feb 22 2001 - 00:34:26 CST

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