---查看内存参数：
sys@PROD>show parameter target;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
archive_lag_target integer 0
db_flashback_retention_target integer 1440
fast_start_io_target integer 0
fast_start_mttr_target integer 0
memory_max_target big integer 800M
memory_target big integer 800M
parallel_servers_target integer 16
pga_aggregate_target big integer 0
sga_target big integer 0
如果pga_aggregate_target 与sga_target两个参数值为零，则为内存自动管理。
---也可以独自查看sga_target参数：
PROD>show parameter sga_target
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
sga_target big integer 0
PROD>
#如果sga_target参数值为0，则共享内存自动管理。---还可以查看workarea_size_policy参数：
sys@PROD>show parameter workarea_size_policy
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
workarea_size_policy string AUTO
sys@PROD>
#该参数有两个值：manual与auto，缺省情况下，为auto值，即自动管理。
---更改内存的管理方式：
--查看数据库版本：
SQL> select * from v$version;
BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
PL/SQL Release 11.2.0.4.0 - Production
CORE 11.2.0.4.0 Production
TNS for Linux: Version 11.2.0.4.0 - Production
NLSRTL Version 11.2.0.4.0 - Production
--确定内存为手动管理：
PROD> show parameter target;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
archive_lag_target integer 0
db_flashback_retention_target integer 1440
fast_start_io_target integer 0
fast_start_mttr_target integer 0
memory_max_target big integer 0
memory_target big integer 0
parallel_servers_target integer 512
pga_aggregate_target big integer 160M
sga_target big integer 640M
--修改为自动管理：
PROD> alter system set sga_target=0 scope=spfile;
System altered.
PROD> alter system set pga_aggregate_target=0 scope=spfile;
System altered.
PROD> alter system set memory_max_target=800M scope=spfile;
System altered.
PROD> alter system set memory_target=800M scope=spfile;
System altered.
--关闭重启数据库使其生效：
PROD> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
PROD> startup;
ORACLE instance started.
Total System Global Area 835104768 bytes
Fixed Size 2257840 bytes
Variable Size 507513936 bytes
Database Buffers 322961408 bytes
Redo Buffers 2371584 bytes
Database mounted.
Database opened.
--确定参数修改成功：
PROD> show parameter target;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
archive_lag_target integer 0
db_flashback_retention_target integer 1440
fast_start_io_target integer 0
fast_start_mttr_target integer 0
memory_max_target big integer 800M
memory_target big integer 800M
parallel_servers_target integer 512
pga_aggregate_target big integer 0
sga_target big integer 0
注：修改的oracle内存不要大于物理内存，这点要检查好单位是GB/MB/KB，否则会出现startup没有任何反应。