Re: ASMM

From: Andrew Kerber <andrew.kerber_at_gmail.com>
Date: Mon, 12 May 2014 10:11:58 -0500
Message-ID: <CAJvnOJZp_6tbi1-Yu_WwSkvrLFBv9AR6Cu96Yoyt3ayxoyaCNA_at_mail.gmail.com>

The classic cause of a low library hit ratio is too much dynamic (ie generated) sql running. IF that is the case, you would also typically see very high CPU usage due to hard parsing. Before you add memory, you should see if you can see the source of the problem.

On Mon, May 12, 2014 at 9:55 AM, Chris Taylor < christopherdtaylor1994_at_gmail.com> wrote:

> First I would caution you on the use of trying to hit some "magical" ratio
> - there are lots of discussions on this topic both on this list and around
> the web (AskTom, Hotsos, Cary Millsap etc)
> Here's a link to a 2003 article at Hotsos:
>
> http://www.hotsos.com/e-library/abstract.php?id=6
>
> ​Now, having said that, what _are_ your pool sizes currently?
>
> select name,bytes/1024/1024 as size_mb
> from v$sgainfo
> /
>
> Next, what is your application profile "look like"? What I mean by that
> is, for the applications that use your database, what does the app do
> inside the database? Is it a lot of straight SQL? A lot of PL/SQL? A
> mix? Does the SQL and PL/SQL use bind variables appropriately, or do you
> have lots of SQL with literal values that are considered "unique"?
>
> If you have a lot of SQL that cannot be shared, this is going to drive
> down that ratio you're looking at. Also if you have anything that is
> flooding the library cache and invalidating previous SQL that will also
> drive down your ration I believe. And there are others as well.
>
> Regards,
> Chris
>
>
>
> On Mon, May 12, 2014 at 9:41 AM, Zelli, Brian <Brian.Zelli_at_roswellpark.org
> > wrote:
>
>> I am finding that my Library Cache Get hit Ratio % is hovering around
>> 50-60 percent. I read that the value should be above 90%. I read that
>> the recommendation is to increase the shared pool size. I am running AMM
>> and I set the memory_target twice what it was and still no relief…..
>>
>>
>>
>>
>>
>> Brian
>>
>>
>>
>>
>>
>> *From:* Chris Taylor [mailto:christopherdtaylor1994_at_gmail.com]
>> *Sent:* Monday, May 12, 2014 10:38 AM
>> *To:* Zelli, Brian
>> *Cc:* oracle-l (oracle-l_at_freelists.org)
>> *Subject:* Re: ASMM
>>
>>
>>
>> Brian,
>>
>>
>>
>> The answer to your question is "it depends". What are you running now?
>> (AMM I assume?) What is your goal? Are you trying to solve a problem you
>> think is related to AMM or a non-AMM configuration? There's not a black
>> and white answer to your question. With some more details people "might"
>> be able to offer some insight/suggestions.
>>
>>
>>
>> Regards,
>>
>> Chris
>>
>>
>>
>

-- 
Andrew W. Kerber

'If at first you dont succeed, dont take up skydiving.'

--
http://www.freelists.org/webpage/oracle-l

Received on Mon May 12 2014 - 17:11:58 CEST