When MEMORY_MAX_TARGET & MEMORY_TARGET are set to 0 , database will run on a variation of ASMM or manual.
If MEMORY_TARGET is set to a non-zero value:
If SGA_TARGET and PGA_AGGREGATE_TARGET are set, they will be considered the minimum values for the sizes of SGA and the PGA respectively. MEMORY_TARGET values can range from SGA_TARGET + PGA_AGGREGATE_TARGET to MEMORY_MAX_TARGET.
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 the minimum non-zero value of MEMORY_TARGET - PGA_AGGREGATE_TARGET and SGA_MAX_SIZE and will auto tune its components.
If neither is set, they will be auto-tuned without any minimum or default values. We will have a policy of distributing the total memory set by MEMORY_TARGET parameter in a fixed ratio to the the SGA and PGA during initialization. The policy is to give 60% to the SGA and 40% to the PGA at startup.
If MEMORY_MAX_TARGET has not been explicitly set, but MEMORY_TARGET has, the instance automatically sets MEMORY_MAX_TARGET to the same value as MEMORY_TARGET. If MEMORY_TARGET has not been explicitly set, but MEMORY_MAX_TARGET has, then MEMORY_TARGET defaults to 0. After instance startup, it then is possible to dynamically change MEMORY_TARGET to a non-zero value, provided that it does not exceed the value of MEMORY_MAX_TARGET.
If MEMORY_TARGET is not set or set to set to 0 explicitly (default value is 0 for 11g):
If SGA_TARGET is set we will only auto-tune the sizes of the components of the SGA. PGA will be autotuned independent of whether it is explicitly set or not. However, the combination of SGA and PGA will not be auto-tuned, i.e. the SGA and PGA will not share memory and resize as with the case of MEMORY_TARGET being set to a non-zero value.
If neither SGA_TARGET nor PGA_AGGREGATE_TARGET is set, we will follow the same policy as we have today; PGA will be auto-tuned and the SGA will not be auto-tuned and parameters for some of the SGA components will have to be set explicitly (for SGA_TARGET).
If only MEMORY_MAX_TARGET is set, MEMORY_TARGET will default to 0 and we will not auto tune the SGA and PGA. It will default to 10gR2 behavior.
If SGA_MAX_SIZE is not user set, it is internally set to MEMORY_MAX_TARGET.
If MEMORY_TARGET is set to a non-zero value:
If SGA_TARGET and PGA_AGGREGATE_TARGET are set, they will be considered the minimum values for the sizes of SGA and the PGA respectively. MEMORY_TARGET values can range from SGA_TARGET + PGA_AGGREGATE_TARGET to MEMORY_MAX_TARGET.
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 the minimum non-zero value of MEMORY_TARGET - PGA_AGGREGATE_TARGET and SGA_MAX_SIZE and will auto tune its components.
If neither is set, they will be auto-tuned without any minimum or default values. We will have a policy of distributing the total memory set by MEMORY_TARGET parameter in a fixed ratio to the the SGA and PGA during initialization. The policy is to give 60% to the SGA and 40% to the PGA at startup.
If MEMORY_MAX_TARGET has not been explicitly set, but MEMORY_TARGET has, the instance automatically sets MEMORY_MAX_TARGET to the same value as MEMORY_TARGET. If MEMORY_TARGET has not been explicitly set, but MEMORY_MAX_TARGET has, then MEMORY_TARGET defaults to 0. After instance startup, it then is possible to dynamically change MEMORY_TARGET to a non-zero value, provided that it does not exceed the value of MEMORY_MAX_TARGET.
If MEMORY_TARGET is not set or set to set to 0 explicitly (default value is 0 for 11g):
If SGA_TARGET is set we will only auto-tune the sizes of the components of the SGA. PGA will be autotuned independent of whether it is explicitly set or not. However, the combination of SGA and PGA will not be auto-tuned, i.e. the SGA and PGA will not share memory and resize as with the case of MEMORY_TARGET being set to a non-zero value.
If neither SGA_TARGET nor PGA_AGGREGATE_TARGET is set, we will follow the same policy as we have today; PGA will be auto-tuned and the SGA will not be auto-tuned and parameters for some of the SGA components will have to be set explicitly (for SGA_TARGET).
If only MEMORY_MAX_TARGET is set, MEMORY_TARGET will default to 0 and we will not auto tune the SGA and PGA. It will default to 10gR2 behavior.
If SGA_MAX_SIZE is not user set, it is internally set to MEMORY_MAX_TARGET.
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