Re: the wonders of automatic sga management

"Charles Hooper" <hooperc2000_at_yahoo.com> wrote in message news:1166192973.065838.237560_at_j72g2000cwa.googlegroups.com...
>
> "You can exercise some control over the size of the automatically sized
> SGA components by specifying minimum values for the parameters
> corresponding to these components. Doing so can be useful if you know
> that an application cannot function properly without a minimum amount
> of memory in specific components. You specify the minimum amount of SGA
> space for a component by setting a value for its corresponding
> initialization parameter. Here is an example configuration:
> SGA_TARGET = 256M
> SHARED_POOL_SIZE = 32M
> DB_CACHE_SIZE = 100M"
>
> Even with automatic SGA tuning enabled, it is possible to specify
> minimum values for various SGA components. For instance, if one were
> to specify a large value for db_cache_size, that would automatically
> reduce the amount of memory available for the other components of the
> SGA, thus setting an upper limit of the shared pool size.
>

I think I sent the following as a private reply - so repeating it below:

    But if you are sufficiently knowledgeable to be able to     work out a minimum, then you don't need automatic     at all. Bear in mind that the feature was sold on the     example of:

    If you have a daytime/night-time pattern where     the daytime needs a large shared pool and the     night-time needs a small shared pool but a large     buffer cache then ...

    In which case just setting "a" minimum doesn't work     anyway.

-- 
Regards

Jonathan Lewis
http://jonathanlewis.wordpress.com

Author: Cost Based Oracle: Fundamentals
http://www.jlcomp.demon.co.uk/cbo_book/ind_book.html

The Co-operative Oracle Users' FAQ
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