sga_target调整大小

sga_target是动态参数，可以调整后马上生效的

但是前提是当前分配的sga_max_size下必须能够承载分配的内存量

这个参数的值只有0和非零两种选择，非零时时和sga_max_size大小保持一致的

所以如果要吧sga_target改成大于sga_max_size的值就必须按照静态参数的改法，重新启动实例

重启后默认的sga_max_size会自动调整到和sga_target一样大小的

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版本

SQL> select * from v$version;

BANNER

--------------------------------------------------------------------------------

Oracle Database 10g Enterprise Edition Release10.1.0.2.0 - Prod

PL/SQL Release 10.1.0.2.0 - Production

CORE 10.1.0.2.0 Production

TNS for 32-bit Windows: Version 10.1.0.2.0 - Production

NLSRTL Version 10.1.0.2.0 - Production

使用spfile

SQL> show parameter spfile

NAME TYPE VALUE

------------------------------------ ---------------------- ------------------------------

spfile string F:\ORACLE\PRODUCT\10.1.0\DB_1\

调整前

SQL> set wrap off

SQL> set linesize 159

SQL> show parameter sga

NAME TYPE VALUE

------------------------------------ ---------------------- ------------------------------

lock_sga boolean FALSE

pre_page_sga boolean FALSE

sga_max_size big integer 300M

sga_target big integer 0

调整为小于sga_max_size值

SQL> alter system set sga_target=200m;

System altered.

SQL> show parameter sga

NAME TYPE VALUE

------------------------------------ ---------------------- ------------------------------

lock_sga boolean FALSE

pre_page_sga boolean FALSE

sga_max_size big integer 300M

sga_target big integer 300M

调整为大于sga_max_size值

SQL> alter system set sga_target=500m;

alter system set sga_target=500m

*

ERROR at line 1:

ORA-02097: parameter cannot be modified because specified value is invalid

ORA-00823: Specified value of sga_target greater than sga_max_size

按照静态参数的方式调整

SQL> alter system set sga_target=500m scope=spfile;

System altered.

SQL> show parameter sga

NAME TYPE VALUE

------------------------------------ ---------------------- ------------------------------

lock_sga boolean FALSE

pre_page_sga boolean FALSE

sga_max_size big integer 300M

sga_target big integer 300M

重启验证

SQL> shutdown immediate

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL> startup

ORACLE instance started.

Total System Global Area 524288000 bytes

Fixed Size 789672 bytes

Variable Size 145486680 bytes

Database Buffers 377487360 bytes

Redo Buffers 524288 bytes

Database mounted.

Database opened.

SQL> show parameter sga

NAME TYPE VALUE

------------------------------------ ---------------------- ------------------------------

lock_sga boolean FALSE

pre_page_sga boolean FALSE

sga_max_size big integer 500M

sga_target big integer 500M