Oracle11g的SGA和PGA設置為多大最合適?

Oracle官方文檔推薦:
MEMORY_TARGET=物理內存 x 80%
MEMORY_MAX_SIZE=物理內存 x 80%

對於OLTP系統： 
SGA_TARGET=(物理內存 x 80%) x 80%
SGA_MAX_SIZE=(物理內存 x 80%) x 80%
PGA_AGGREGATE_TARGET=(物理內存 x 80%) x 20%

對於DSS系統：
SGA_TARGET=(物理內存 x 80%) x 50%
SGA_MAX_SIZE=(物理內存 x 80%) x 50%
PGA_AGGREGATE_TARGET=(物理內存 x 80%) x 50%