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memory_max_target and 11g memory utilization - question [message #533590]

Wed, 30 November 2011 12:37

piotrtal
Messages: 168
Registered: June 2011
Location: Poland/Czestochowa

Senior Member

Hi,

I will ask one question and will try to define my problem after some answers.

Please straighten me because I may be wrong.
Is it possible than if i have Automatic Memory Management enabled (AMM) process of oracle will utilize more than parameter memory_max_target is set?

For example:
memory_max_target=16G
memory_target=16G
pga_aggregate_target=0G
sga_target=0G

is it possible that overall memory utilized by process oracle.exe (windows 2008) is more than 16GB during high system overload?

thanks.

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Re: memory_max_target and 11g memory utilization - question [message #533592 is a reply to message #533590]

Wed, 30 November 2011 12:50

Michel Cadot
Messages: 68641
Registered: March 2007
Location: Nanterre, France, http://...

Senior Member
Account Moderator

Yes, it is possible.

Regards
Michel

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Re: memory_max_target and 11g memory utilization - question [message #533593 is a reply to message #533592]

Wed, 30 November 2011 13:09

piotrtal
Messages: 168
Registered: June 2011
Location: Poland/Czestochowa

Senior Member

Michel Cadot wrote on Wed, 30 November 2011 19:50

Yes, it is possible.

Regards
Michel

hm. so I was wrong.

I know that memory_max_target specify memory which oracle could redistribute between SGA and PGA, but I was 100% sure that it protect also againts overutilizing memory.

this thing happened to me today during execution complicated query oracle created process which utilized 15G in several seconds. system started swapping on disk and everything slowed down. the only think which i could do was orakill specified process.

Michael could you extend your answer? I digged on many web pages and nowhere there was info about that oracle can utilize much more memory than memory_max_target.

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Re: memory_max_target and 11g memory utilization - question [message #533594 is a reply to message #533593]

Wed, 30 November 2011 13:15

BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal

Senior Member

when all else fails Read The Fine Manual

http://docs.oracle.com/cd/E11882_01/server.112/e25513/initparams140.htm#REFRN10285

"Total memory usage can grow beyond the value of MEMORY_TARGET. For example, memory is allocated to PL/SQL tables and varrays regardless of the value of MEMORY_TARGET as long as memory is available at the operating system level."

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Re: memory_max_target and 11g memory utilization - question [message #533595 is a reply to message #533594]

Wed, 30 November 2011 13:20

piotrtal
Messages: 168
Registered: June 2011
Location: Poland/Czestochowa

Senior Member

thanks for answer.

indeed, i didn't know that.

does oracle have parameters which could prevent from overutilizing memory, or it can get as much as is availabile in physical and swap file?

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Re: memory_max_target and 11g memory utilization - question [message #533596 is a reply to message #533595]

Wed, 30 November 2011 13:27

BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal

Senior Member

PL/SQL tables and varrays are evil & should *NOT* be part of Production application.
Oracle can not always protect itself from rogue DUHvelopers, but enforced coding standards can avoid performance problems.

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