Kirti
Thanks for the info.
I could not raise dynamically the size of db_cache_size and did not
know why, until I noticed the new parameter sga_max_size. Anyway, I
tried to lower the size of db_cache_size dynamically and I did not have
a problem. So sgma_max_size does play its role in db_cache_sizing.
I have not tested where I increase the size of sga_max_size using
init.ora and then try to increase the size of db_cache_size dynamically
by the same size as the increase in sga_max_size. That is the test for
coming weekend.
- Kirtikumar Deshpande <kirtikumar_deshpande_at_yahoo.com> wrote:
> SGA_MAX_SIZE was introduced in 9i to allow dynamic sizing of SGA
> (Dynamic Sizing feature)
> components such as, shared pool, large pool, buffer cache etc. In
> versions up to 8i, such changes
> required bouncing the instance.
> This parameter assumes the value of the SGA at instance startup.
> Various components of the SGA can
> then be increased/reduced as and when needed. The total SGA, thus,
> can reach a maximum value set
> by SGA_MAX_SIZE (if set in the init.ora file). That's the idea.
> However, the implementation is
> different on various platforms. With ISM, and DISM, on Solaris, there
> are other issues when it
> comes to using Dynamic SGA. You may want to search Metalink for
> specific notes/articles for
> Solaris.
> On AIX 5L as I found out, Oracle uses SGA_MAX_SIZE, if set in
> init.ora, at the instanace startup,
> and allocates the excess (difference in computed SGA value and set
> SGA_MAX_SIZE) to 'variable
> size'. Hence there is no room for any dynamic sizing (upward) of any
> SGA component. I did not try
> to downsize shared pool first, and 'upsize' buffer cache later. May
> be that would work, but that
> is not the intention of using this parameter.
>
> PGA_AGRREGATE_TARGET is completely different from this parameter. It
> sets an instance-wide upper
> limit for the memory used by sorting, hashing processes.
>
> Hope this helps..
>
> - Kirti
>
>
> --- Mohammed Shakir <mshakir08816_at_yahoo.com> wrote:
> > I am little confused about this issue to. I am working on Oracle
> > 9.2.0.3 on Solaris 9 (64 bits) platform. I did not set sga_max_size
> > parameter and I see it set. I am not sure what it means and what
> kind
> > of problem it will cause me.
> >
> > I have pga_aggregate_target is set for 512MB and it seems it is not
> > counted in this count. I know it is a separate space in the memory.
> > Since this is a new system for me, I am little concerned that
> Oracle
> > does not chock on me.
> >
> > --- Kirtikumar Deshpande <kirtikumar_deshpande_at_yahoo.com> wrote:
> > > It does not work as advertised, in AIX either... I played with
> this
> > > in AIX 5L.
> > >
> > >
> > > - Kirti
> > >
> > >
> > >
>
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Received on Mon Aug 04 2003 - 14:49:23 CDT
