Oracle 11g db_ultra_safe参数

db_ultra_safe是Oracle 11g新增的参数，可以用来控制db_block_checking, db_block_checksum和db_lost_write_protect三个参数的值。

db_ultra_safe的取值是off, data_only, data_and_index

其中off是缺省值。表示db_ultra_safe不会影响其它三个参数的设置值。

data_only, 相当于:

db_block_checking=medium

db_block_checksum=full

db_lost_write_protect=typical

data_and_index, 相当于:

db_block_checking=full

db_block_checksum=full

db_lost_write_protect=typical

示例：

• 系统的缺省值

SQL> show parameter db_ultra

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_ultra_safe                        string      OFF
SQL> show parameter db_block_check

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_block_checking                    string      FALSE
db_block_checksum                    string      TYPICAL
SQL> show parameter db_lost

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_lost_write_protect                string      NONE

• 修改db_ultra_safe为data_only

SQL> alter system set db_ultra_safe=data_only;
alter system set db_ultra_safe=data_only
                 *
ERROR at line 1:
ORA-02095: specified initialization parameter cannot be modified

此参数不能动态修改

SQL> alter system set db_ultra_safe=data_only scope=spfile;

System altered.

SQL> shutdown immediate;
SQL> startup;

SQL> show parameter db_ultra

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_ultra_safe                        string      DATA_ONLY
SQL> show parameter db_block_check

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_block_checking                    string      MEDIUM
db_block_checksum                    string      FULL
SQL> show parameter db_lost

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_lost_write_protect                string      TYPICAL

修改db_ultra_safe值后，其它三个参数值自动修改。

• 修改db_ultra_safe为data_and_index

SQL> alter system set db_ultra_safe=data_and_index scope=spfile;

System altered.

SQL> shutdown immediate;

SQL> startup;

SQL> show parameter db_ultra

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_ultra_safe                        string      DATA_AND_INDEX
SQL> show parameter db_block_check

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_block_checking                    string      FULL
db_block_checksum                    string      FULL
SQL> show parameter db_lost

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_lost_write_protect                string      TYPICAL