How oracle determine the value of optimal_size and onepass_size to use during pga_aggregate_target

Hi,  

I am trying to understand the algorithm used by Oracle when using pga_aggregate target and it looks like to get the information on Expected_WorkAreaSize, Oracle already knows about the value of optimal_size(cache size) and onepass_size so I was wondering how oracle calculate this values. Also in the same white paper it is mentioned that to sort the 10GB of input data Oracle only needs about 40MB for 1 pass but I thought to sort 10gb using 40MB bucket we need lot of passes so how it calcuate this 40MB for onepass.  

Thanks

--Harvinder
 

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http://www.freelists.org/webpage/oracle-l Received on Wed May 16 2007 - 15:06:14 CDT