Oracle 配置 Multiple Block Sizes 表空间 - 数据库编程

K_SIZE has a value other than nK. For example, ifDB_BLOCK_SIZE=4096, then it is illegal to specify the parameterDB_4K_CACHE_SIZE (because the size for the 4 KB block cache is alreadyspecified by DB_CACHE_SIZE).

-- DB_nK_CACHE_SIZE 参数指定nK 的buffer，在指定cache时，要确保有足够的空间。不能和DB_BLOCK_SIZE参数冲突，n 可以取2，4，8，16，32.

Donot set this parameter to zero if there are any online tablespaces with an nKblock size.

Operating system-specific block size restrictions apply.For example, you cannot set DB_32K_CACHE_SIZE if the operating system's maximumblock size is less than 32 KB. Also, you cannot set DB_2K_CACHE_SIZE if theminimum block size is greater than 2 KB.

-- DB_nK_CACHE_SIZE要操作系统支持，如果n=32，但操作系统支持，也是不行的。

See Also:

Youroperating system-specific Oracle documentation for more information on blocksize restrictions

二. 测试

--查看db_block_size

SYS@anqing2(rac2)> show parameterdb_block_size

NAME TYPE VALUE

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

db_block_size integer 8192

--查看操作系统位数

[root@rac2 ~]# cat /proc/cpuinfo | grepflags | grep 'lm' | wc -l

结果大于0, 说明支持64bit计算. lm指long mode, 支持lm则是64bit。

有关CPU的更多信息参考：

Linux CPU 信息查看

http://blog.csdn.net/tianlesoftware/article/details/5970500

--查看db_32k_cache_size值

SYS@anqing2(rac2)> show parameterdb_32k_cache_size

NAME TYPE VALUE

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

db_32k_cache_size big integer 0

-- 指定32k 时，报错，提示系统不支持，看来只能用16k了

SYS@anqing1(rac1)> alter system setdb_32k_cache_size=1M scope=both sid='anqing1';

alter system set db_32k_cache_size=1Mscope=both sid='anqing1'

ERROR at line 1:

ORA-32017: failure in updating SPFILE

ORA-00382: 32768 not a valid block size,valid range [..]

--指定16k 的cachebuffer

SYS@anqing1(rac1)> alter system set db_16k_cache_size=1M scope=bothsid='anqing1';

System altered.

SYS@anqing2(rac2)> alter system set db_16k_cache_size=1M scope=bothsid='anqing2';

System altered.

-- 因为我的测试环境是RAC，所以在2个节点上都指定了参数

--查看cache，虽然指定了1M，但系统使用了默认的最小值

SYS@anqing1(rac1)> show parameter db_16k_cache_size

NAME TYPE VALUE

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

db_16k_cache_size big integer 4M

SYS@anqing2(rac2)> show parameter db_16k_cache_size

NAME TYPE VALUE

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

db_16k_cache_size big integer 4M

-- 这个最小的默认值，上面的官网说明有解释：

--values greater thanzero are automatically modified to be either the granule size * number ofprocessor groups, or 4 MB * number of CPUs, whichever is greater

--指定了16kcache，我们就可以创建block 为16k的表空间了

SYS@anqing1(rac1)> CREATE TABLESPACETest DATAFILE

2 '+DATA/anqing/datafile/test01.dbf' SIZE 50M AUTOEXTEND ON NEXT 10MMAXSIZE 100M BLOCKSIZE 16K;

Tablespace created.

-- 注意这里指定了Blocksize为16k，和我们之前创建的Cache 大小相对应。

--为了验证不指定cache报的错误，我们创建一个4k的tablespace

SYS@anqing1(rac1)> CREATE TABLESPACE TTDATAFILE '+DATA/anqing/datafile/TT01.dbf' SIZE 50M AUTOEXTEND ON NEXT 10MMAXSIZE 100M BLOCKSIZE 4K;

CREATE TABLESPACE TT DATAFILE'+DATA/anqing/datafile

Oracle 配置 Multiple Block Sizes 表空间(二)