Automatic Memory Management ( Oracle 11g New Features)
Well in 10g SGA can be auto tune and 11g it extended to PGA as well ie SGA and PGA both can auto tune
( i would say , i understood this much only
11g memory management = SGA auto tune + PGA auto tune )
For auto memory, we need to set parameter MEMORY_TARGET and MEMORY_MAX_TARGET. Parameter MEMORY_TARGET is dynamic, we can change the target memory size at any time without restarting the database. The MEMORY_MAX_TARGET serves as an upper limit so that we cannot by mistake set the MEMORY_TARGET size too high. Because certain SGA components eithercannot easily shrink or must remain at a minimum size, the database also prevents you from setting thetarget memory size too low.
If MEMORY_TARGET is set to a non-zero value:
- If SGA_TARGET and PGA_AGGREGATE_TARGET are set, they will be considered the min value for the sizes of SGA and the PGA respectively. MEMORY_TARGET can take values from SGA_TARGET + PGA_AGGREGATE_TARGET to MEMORY_MAX_SIZE.
- If SGA_TARGET is set and PGA_AGGREGATE_TARGET is not set, we will still auto-tune both parameters. PGA_AGGREGATE_TARGET will be initialized to a value of (MEMORY_TARGET-SGA_TARGET).
- If PGA_AGGREGATE_TARGET is set and SGA_TARGET is not set, we will still auto-tune both parameters. SGA_TARGET will be initialized to a value of min(MEMORY_TARGET-PGA_AGGREGATE_TARGET, SGA_MAX_SIZE (if set by the user)) and will auto-tune subcomps.