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RE: Questions about automatic memory allocations in 10g (r1 and r2)

From: Kevin Closson <>
Date: Thu, 20 Oct 2005 11:26:42 -0700
Message-ID: <>


> I was in a meeting yesterday with a vendor who told me (and my
manager) their product running on 10gr1 does not
> need any DBA intervention when used because they are using automatic
memory management and they use "all of physical
> memory ... for the SGA".
>Now, this person is no Oracle DBA/expert/guru. He has attended a class
like "New features in 10g" or something like that. When I questioned this "use all of physical memory" strategy and how that might affect PGA usage, he was stumped.

...that this person is no guru is an understatement. that he bought off on
the marketing patch that 10g needs no human intervention when he attended
the "New features in 10g" doesn't surprise me at all. Oracle's Marketing prowess cancels out what little attention to detail the average DBA seems
to have left anymore.

Long before the PGA starts to wrestle this supposed total phys mem SGA, there is amonst other goodies a Kernel, text, page tables, initialized data,
and stack.

Even though this non-guru DBA you refer to doesn't know squat about what the OSDs do to get shared memory (or what OSDs are), he's likely try to open a tar when the shmget() fails to create a segment equal to phys mem. Then, the "support technician" will open the "New features in 10g" slideset and try to open a bug against the base! :-)

BTW, I would counsel any IT shop to NOT send ANYONE to an Oracle "New features in XYZ" class unless they have a minimum of 10 years production DBA experience. Only the most senior of the IT shop need to get their heads around the stuff that will be of interest 4 years after it is heralded in a "New features in XYZ" class. Otherwise, best of luck when half-baked new features get thrown into production.  

Received on Thu Oct 20 2005 - 13:29:18 CDT

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