Re: Pga is growing on 11.2.2.0

From: MARK BRINSMEAD <mark.brinsmead_at_gmail.com>
Date: Tue, 14 Apr 2015 17:49:55 -0400
Message-ID: <CAAaXtLDTgAv43iuJpEKOCrgMPzGL-yEjAEewQNasXtVi=L0eZA_at_mail.gmail.com>

You're no dinosaur, as far as I am concerned.

But then, we share common roots, so maybe I am just a dinosaur, too.

For those who *do* prefer to (insist on) using AMM / ASMM, so be aware that you can still specify sizes for each of the major pools of memory. The value you specify become the *minimum* size for the pool in question. Doing this, you can prevent the PGA from growing out of control and shrinking your buffer cache into oblivion.

Setting sensible lower bounds for all of the pools can also go a long way toward reducing the "thrashing" of memory that Don refers to, but the only way to eliminate it completely is to allocate memory manually.

On Tue, Apr 14, 2015 at 12:16 PM, Don Seiler <don_at_seiler.us> wrote:

> Not exactly answering your question, but your last comment about the
> buffer cache shrinking is why I dislike auto memory management. I set
> memory_target and sga_target to 0 in my prod and dev environments where I
> want a stable profile for app testing.
>
> I'm probably a dinosaur and way behind in feature adoption, but I've been
> burned by AMM thrashing the hell out of memory in the past as well.
>
> Don.
>
> On Tue, Apr 14, 2015 at 8:12 AM, walid kaakati <
> dmarc-noreply_at_freelists.org> wrote:
>
>> Hi List,
>>
>> We are running Oracle 11g 11.2.0.2 on windows Server 2008,i have set
>> memory_target to 24GB.
>>
>> After a few days i see the SGA =9088 MB and PGA=15488 MB, the PGA Cache
>> Hit % is 76,31 , in the ADDM i see actual used memory for PGA is only 400
>> MB ! , beside this Memory Target Advisor shows that i need to increase PGA
>> to 18586 MB to get PGA cache hit ratio 90 %,
>>
>> My question is this normal ??! how i limit the the size of PGA ? through
>> the time the buffer cache is decreasing for more PGA allocations !
>>
>>
>> Best wishes
>>
>
>
>
> --
> Don Seiler
> http://www.seiler.us
>

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Received on Tue Apr 14 2015 - 23:49:55 CEST