11g Memory Parameters

MEMORY_TARGET triggers automatic memory management.  Here are the rules:

  • If SGA_TARGET and PGA_AGGREGATE_TARGET are set, they will be considred to be minimum values for the sizes of SGA and PGA.  
  • SGA_TARGET is set but PGA_AGGREGATE_TARGET is not set, it is equal to MEMORY_TARGET - SGA_TARGET
  • If PGA_AGGREGATE_TARGET is set and SGA_TARGET is not set, SGA_TARGET is initialized to MEMORY_TARGET - PGA_TARGET
  • If neither is set, 60% is ditributed to SGA and 40% is distributed to PGA at startup.
  • If MEMORY_TARGET is not set, they're not auto-tuned.
  • If MEMORY_MAX_TARGET is set and MEMORY_TARGET   = 0, auto-tune behavior defaults to 10gR2 behavior.
The following views provide memory information:
  • V$MEMORY_DYNAMIC_COMPONENTS:  Shows the current size of all dynamically tuned memory components.
  • V$MEMORY_RESIZE_OPS:  Shows information about the last 800 completed memory resize operations.
  • V$MEMORY_CURRENT_RESIZE_OPS:  Shows the current/in progress resize operations both manual and dynamic.
  • V$SGA_DYNAMIC_COMPONENTS:  Summarizes all dynamic SGA resize operation since startup
  • V$SGA_DYNAMIC_FREE_MEMORY:  Shows the amount of memory is available for futhre dynamic SGA resize operation.


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