The PGA Memory Advisor, much like the buffer pool advisory report, provides some insight into how to properly size your PGA via the PGA_AGGREGATE_TARGET database parameter.

			In this section, you first need to find the row with the Size Factr column value of 1.0. 
			
			This column indicates the size factor of the PGA estimates; a value of 1 indicates the current PGA size. 

			The PGA Target Est(MB) value of this row will show your current PGA size: 14,133 MB in this example. 

			Other columns you will be interested in are Estd Extra W/A MB Read/Written to Disk and Estd PGA Overalloc Count.

			When you go down or up the advisory section from the row with Size Factr = 1.0, you get estimates for Disk 
			usage - column Estd Extra W/A MB Read/Written to Disk - for bigger or smaller settings of PGA_AGGREGATE_TARGET. 

			The less Disk usage figure in this column, usually the better. A lower value means less work areas have to be 
			spilled to disk, enhancing performance of the Oracle instance.
			
			Your first goal is to have such a setting of PGA_AGGREGATE_TARGET, that number in the column Estd Extra W/A MB Read/Written 
			to Disk does not substantially reduce any more. 
			
			In the example output this happens at value 12,335.96 In other words, further increases of PGA_AGGREGATE_TARGET won't give 
			any substantial benefit and will only waste memory. 
			
			The row corresponding to this value shows a Size Factr column value of 1.20, indicating that the current PGA size should be 
			increased 1.20 times (to 17,203 MB) to reach this goal.
			
			The Estd PGA Overalloc Count column shows how many times the database instance PROCESSES would need to request more PGA memory 
			at the OS level than the amount shown in the PGA Target Est (MB) value of the respective row. 
			
			Ideally this field should be 0 (indicating that the PGA is correctly sized, and no overallocations should take place), and 
			that is your equally important second goal. 
			
			In the given example this goal is achieved with PGA_AGGREGATE_TARGET = 17,203MB.