What is new in Automatic Memory Management 11g
New parameters are:
1) MEMORY_TARGET
2) MEMORY_MAX_TARGET
why is the requirement of those two parameters?
Oracle DB instance contains SGA memory + PGA memory. they are controlled by sga_target and pga_aggregate_target parameters in 10g. But imagine the scenario where you have allotted more sga value and instance is running out of pga target, or instance running out of sga but there are plenty alloted to pga. To avoid this scenario, 11g has come up with memory_target (where instance automatically tunes up or down sga and pga values to memory_target you specify). Memory_max_target specifies the upper limit of memory_target. You can extend you memory_target value up to memory_max_target without restarting your DB.
You set memory_max_target to the value that OS can give to this instance. (if you have 2 db instances you may have to split the portions according to the usage of the instances). and memory_target is dynamic parameters you can modify whenever you want but not exceeding memory_max_target.
Init.ora Parameters:
memory_max_target = 100M
memory_target = 80M
V$MEMORY_DYNAMIC_COMPONENTS
The dynamic performance view V$MEMORY_DYNAMIC_COMPONENTS shows the current sizes of all dynamically tuned memory components, including the total sizes of the SGA and instance PGA.
New parameters are:
1) MEMORY_TARGET
2) MEMORY_MAX_TARGET
why is the requirement of those two parameters?
Oracle DB instance contains SGA memory + PGA memory. they are controlled by sga_target and pga_aggregate_target parameters in 10g. But imagine the scenario where you have allotted more sga value and instance is running out of pga target, or instance running out of sga but there are plenty alloted to pga. To avoid this scenario, 11g has come up with memory_target (where instance automatically tunes up or down sga and pga values to memory_target you specify). Memory_max_target specifies the upper limit of memory_target. You can extend you memory_target value up to memory_max_target without restarting your DB.
You set memory_max_target to the value that OS can give to this instance. (if you have 2 db instances you may have to split the portions according to the usage of the instances). and memory_target is dynamic parameters you can modify whenever you want but not exceeding memory_max_target.
Init.ora Parameters:
memory_max_target = 100M
memory_target = 80M
V$MEMORY_DYNAMIC_COMPONENTS
The dynamic performance view V$MEMORY_DYNAMIC_COMPONENTS shows the current sizes of all dynamically tuned memory components, including the total sizes of the SGA and instance PGA.
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