In DWH DB ( 12c) OEM reports PGA cache Hit Ratio 76% .
Values from Enterprise Manager ( 12c )
Current Allocated : 20G
Max allocated : 116 G
pga_aggregate_target : 100G
pga_aggregate_limit : 200G
Server has 700 GB Memory. Only about 60% is used at the moment. Why Hit Ratio is so small if the limit is 200G and max allocated 116G ?