Oracle 11g PGA advice view is empty when it shouldn't
Bug 11872813 - V$PGA_TARGET_ADVICE VIEW IS EMPTY.


  After setting PGA_AGGREGATE_TARGET > approximately 12G the
  V$PGA_TARGET_ADVICE view is empty.
  This issue will be fixed in version 12.1 and a fix is expected to be included  in patch set
  11.2.0.4.
  
  Apply Patch 11872813