日期:2014-05-16  浏览次数:20518 次

在Oracle 11g中用看Oracle的共享内存段---------IPCS

很早之前,在一次讲课了,用了命令ipcs,发现oracle的共享内段好小,如下:

oracle@mydb ~]$ ipcs -a

------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status      
0x00000000 32768      root      644        72         2                       
0x00000000 65537      root      644        16384      2                       
0x00000000 98306      root      644        280        2                       
0x00000000 1409028    oracle    640        4096       0                       
0x00000000 1441797    oracle    640        4096       0                       
0x079918e8 1474566    oracle    640        4096       0                       

------ Semaphore Arrays --------
key        semid      owner      perms      nsems     
0x87a36da4 1343489    oracle    640        154       

------ Message Queues --------
key        msqid      owner      perms      used-bytes   messages   

今天突然想起,刚好有空,来总结一下:

上面显示Oracle共享内存段只有4096个字节,这太小了吧,哦,对了,我这是Oracle11g:

sys@OCM> select * from v$version;

BANNER
--------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
PL/SQL Release 11.2.0.3.0 - Production
CORE    11.2.0.3.0      Production
TNS for Linux: Version 11.2.0.3.0 - Production
NLSRTL Version 11.2.0.3.0 - Production

Oraccle11g的对内存的管理用了两个新的参数:

sys@OCM> show parameter memory

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
hi_shared_memory_address             integer     0
memory_max_target                    big integer 1G
memory_target                        big integer 0
shared_memory_address                integer     0



会不会是参数memory_max_target在作怪呢,把它关了试试,我这里把它设为0,然后重启数据库。

sys@OCM> alter system set memory_max_target=0 scope=spfile;

System altered.

sys@OCM> startup force;
ORACLE instance started.

Total System Global Area  943669248 bytes
Fixed Size                  2234000 bytes
Variable Size             541067632 bytes
Database Buffers          394264576 bytes
Redo Buffers                6103040 bytes
Database mounted.
Database opened.


再看共享内存:

[oracle@mydb ~]$ ipcs -a

------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status      
0x00000000 32768      root      644        72         2                       
0x00000000 65537      root      644        16384      2                       
0x00000000 98306      root      644        280        2                       
0x00000000 1802244    oracle    640        4096       0                       
0x00000000 1835013    oracle    640        4096       0                       
0x079918e8 1867782    oracle    640        4096       0                       

------ Semaphore Arrays --------
key        semid      owner      perms      nsems     
0x87a36da4 1736705    oracle    640        154       

------ Message Queues --------
key        msqid      owner      perms      used-bytes   messages    


怎么回事,没变啊?

是不是参数没改对,继续校验参数:

sys@OCM> show parameter mem

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
hi_shared_memory_address             integer     0
memory_max_target                    big integer 904M
memory_target                        big integer 0
shared_memory_address                integer     0

果然没改过来,是不是命令alter system set memory_max_target=0 scope=spfile;没用啊,不能怎么设,但这命令本身设置重启也没报错。

来个狠一点的命令重置默认