pga_aggregate_target

Hello List,

I was little confused about the settings of pga_aggregate_target
parameter. I was in a assumption that when we set this parameter to a
certain value, the usage of pga wont go beond this value. I have set
pga as 3gb to one of my business critical database. Recently, I have
found that max pga allocation was 4+ Gb. My boss askmed me, why the
hell it takes more than what we have defined. I explained him saying
that oracle might taken it from the OS to finish the necessary
request. His immediately counter question was, then what is the use of
setting pga_aggregate_target parameter? When oracle allocates and
de-allocated the memory (pga) as per requirements.
Is it expected behaviour that oracle takes sometime more that the
value defined for pga? If so, what is the benift of setting value for
pga?
Thanks for your time.


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Best Regards,
Syed Jaffar Hussain
OCP 8i & 9i DBA,
Banque Saudi Fransi,
Saudi Arabia
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"Winners don't do different things. They do things differently."
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http://www.freelists.org/webpage/oracle-l


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