pga使用的一些資料

參考

9i (and probably 10gR1, which I did not test):
_pga_max_size: default value is 200MB.
_smm_max_size : default value is the least of 5% of pga_aggregate_target and of 50% of _pga_max_size. A ceiling of 100MB also applies. The ceiling is hit when the pga_aggregate_target exceeds 2GB (5% of 2GB = 10MB) or
when
_pga_max_size is set to a higher value than the default AND pga_aggregate_target is lower than 2GB.
10gR2
pga_aggregate_target now drives in most cases _smm_max_size:
pga_aggregate_target <=500MB, _smm_max_size = 20%* pga_aggregate_target
pga_aggregate_target between 500MB and 1000MB, _smm_max_size = 100MB
pga_aggregate_target >1000MB, _smm_max_size = 10%* pga_aggregate_target
and _smm_max_size in turns now drives _pga_max_size: _pga_max_size = 2 * _smm_max_size
A pga_aggregate_target larger than 1000MB will now allow much higher default thresholds in 10gR2: pga_aggregate_target set to 5GB will allow an _smm_max_size of 500MB (was 100MB before) and _pga_max_size of 1000MB (was 200MB).
You can get the hidden parameter values by querying x$ksppcv and x$ksppi as follows:
select a.ksppinm name, b.ksppstvl value from sys.x$ksppi a,sys.x$ksppcv b where a.indx = b.indx and a.ksppinm=’_smm_max_size’;
select a.ksppinm name, b.ksppstvl value from sys.x$ksppi a,sys.x$ksppcv b where a.indx = b.indx and a.ksppinm=’_pga_max_size’;

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