RE: Manual vs Auto PGA

  • From: "Lawie, Duncan" <duncan.lawie@xxxxxxxxxxxxxxxxx>
  • To: "'deepak_blr@xxxxxxxxxxx'" <deepak_blr@xxxxxxxxxxx>, "'ORACLE-L'" <oracle-l@xxxxxxxxxxxxx>
  • Date: Tue, 2 Jan 2007 14:29:09 -0000

Individual sessions can't normally take more than 5% of the total value of 
pga_aggregate_target.

  _____  

From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On 
Behalf Of blr_dba
Sent: 30 December 2006 15:01
To: 'ORACLE-L'
Subject: Manual vs Auto PGA


Hi Gurus.
 
My query is using big hash joins. I had set PGA_AGGREGATE_TARGET=4GB. But when 
I observed the pga statistics, I found that the max. pga used by a session is 
300M. That was the only user session running. 

Later I used manual PGA and defined the hash_area_size=2GB explicitly. Then 
oracle started using the whole hash_area and the query ran faster. 

Would like to know why oracle did not allocated teh desired hash_area_size when 
I used auto PGA? 

Are there any situations where we should use manual pga? 


Anything I missed? 

 
Deep


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