212.Note the following parameters settings in your database:

SGA_MAX_SIZE = 1024M

SGA_TARGET = 700M

DB_8K_CACHE_SIZE = 124M

LOG_BUFFER = 200M

You issued the following command to increase the value of DB_8K_CACHE_SIZE:

SQL> ALTER SYSTEM SET DB_8K_CACHE_SIZE=140M;

What would happen?

A. It will fail because DB_8K_CACHE_SIZE parameter cannot be changed dynamically

B. It will be successful only if the memory is available from the auto tuned components

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C. It will fail because an increase in DB_8K_CACHE_SIZE cannot be accommodated within SGA_TARGET

D. It will fail because an increase in the DB_8K_CACHE_SIZE cannot be accommodated within SGA_MAX_SIZE

Answer: D

答案解析：

注意：这道题没有说明该数据库的标准块是8K。

其实在大多数我们的数据库标准块的大小为8K，所以就有了以下不能更新的问题，

但如果数据库的标准块不是8K，则是可以更改的。只要满足总的不能超过SGA_MAX_SIZE就可以了。

所以D应该算是对的。

13:56:20 sys@TEST1107> ALTER SYSTEM SET DB_8K_CACHE_SIZE=140m;

ALTER SYSTEM SET DB_8K_CACHE_SIZE=140m

*

ERROR at line 1:

ORA-32017: failure in updating SPFILE

ORA-00380: cannot specify db_8k_cache_size since 8K is the standard block size

[oracle@rtest ~]$ oerr ora 00380

00380, 00000, "cannot specify db_%sk_cache_size since %sK is the standard block size"

// *Cause:  User specified the parameter db_nk_cache_size (where n is one of

//          2,4,8,16,32), while the standard block size for this database is

//          equal to n Kbytes. This is illegal.

// *Action: Specify the standard block size cache using db_cache_size (DEFAULT

//          pool) (and db_recycle_cache_size, db_keep_cache_size if additional

//          buffer pools are required). Do NOT use the corresponding

//          db_nk_cache_size parameter for the standard block size.

14:00:02 sys@TEST1107> ALTER SYSTEM SET db_cache_size=140m;

System altered.

因为总的SGA_MAX_SIZE为1024M,如果把DB_8K_CACHE_SIZE 设置为140M，则700M+200M+140M=1040M，超过了1024M，会报错。