一 什么是SMON进程 The systemmonitor performs recovery when a failed instance starts up again. In an OracleReal Application Clusters database, the SMON process of one instance canperform instance recovery for other instances that have faile
一 什么是SMON进程
The systemmonitor performs recovery when a failed instance starts up again. In an OracleReal Application Clusters database, the SMON process of one instance canperform instance recovery for other instances that have failed. SMON alsocleans up temporary segments that are no longer in use and recovers deadtransactions skipped during system failure and instance recovery because offile-read or offline errors. These transactions are eventually recovered bySMON when the tablespace or file is brought back online.
作用:
实例恢复
前滚所有重做日志中的改变
打开数据库为了用户能访问
回滚没有提交的事务
接合自由的空间(Coalesce every three secons)
释放临时表空间(Deal Located)
二 操作示例
SQL> startup force; ORACLE instance started. Total System Global Area 838860800 bytes Fixed Size 1222192 bytes Variable Size 775948752 bytes Database Buffers 58720256 bytes Redo Buffers 2969600 bytes Database mounted. Database opened. SQL> startup force mount; ORACLE instance started. Total System Global Area 838860800 bytes Fixed Size 1222192 bytes Variable Size 775948752 bytes Database Buffers 58720256 bytes Redo Buffers 2969600 bytes Database mounted. --出现此问题:关闭数据库,然后重启 SQL> alter database archivelog; alter database archivelog * ERROR at line 1: ORA-00265: instance recovery required, cannot set ARCHIVELOG mode SQL> shutdown immediate; ORA-01109: database not open Database dismounted. ORACLE instance shut down. SQL> startup; ORACLE instance started. Total System Global Area 838860800 bytes Fixed Size 1222192 bytes Variable Size 775948752 bytes Database Buffers 58720256 bytes Redo Buffers 2969600 bytes Database mounted. Database opened. SQL> shutdown mount; SP2-0717: illegal SHUTDOWN option SQL> shutdown immediate; Database closed. Database dismounted. ORACLE instance shut down. SQL> startup mount; ORACLE instance started. Total System Global Area 838860800 bytes Fixed Size 1222192 bytes Variable Size 775948752 bytes Database Buffers 58720256 bytes Redo Buffers 2969600 bytes Database mounted. SQL> alter database noarchivelog; Database altered. SQL> alter database open; Database altered.
三 总结
1. SMON:系统监控进程,静态注册监听
2.SMON作用:实例恢复、接合自由的空间(Coalesceevery three secons)、
释放临时表空间(Deal Located)
<span><span>我的邮箱</span></span><span>:</span>wgbno27@163.com <span> <span>新浪微博</span></span><span>:</span>@Wentasy27 <span>微信公众平台</span>:JustOracle(微信号:justoracle) <span>IT交流群</span>:336882565(加群时验证 From CSDN XXX) <span>Oracle交流讨论组</span>:https://groups.google.com/d/forum/justoracle <span><strong>By Larry Wen</strong></span>
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oracle asm指的是“自动存储管理”,是一种卷管理器,可自动管理磁盘组并提供有效的数据冗余功能;它是做为单独的Oracle实例实施和部署。asm的优势:1、配置简单、可最大化推动数据库合并的存储资源利用;2、支持BIGFILE文件等。

方法:1、利用“select*from user_indexes where table_name=表名”语句查询表中索引;2、利用“select*from all_indexes where table_name=表名”语句查询所有索引。

在Oracle中,可利用lsnrctl命令查询端口号,该命令是Oracle的监听命令;在启动、关闭或重启oracle监听器之前可使用该命令检查oracle监听器的状态,语法为“lsnrctl status”,结果PORT后的内容就是端口号。

在oracle中,可以利用“TO_SINGLE_BYTE(String)”将全角转换为半角;“TO_SINGLE_BYTE”函数可以将参数中所有多字节字符都替换为等价的单字节字符,只有当数据库字符集同时包含多字节和单字节字符的时候有效。

在oracle中,可以利用“drop sequence sequence名”来删除sequence;sequence是自动增加数字序列的意思,也就是序列号,序列号自动增加不能重置,因此需要利用drop sequence语句来删除序列。

在oracle中,可以利用“select ... From all_tab_columns where table_name=upper('表名') AND owner=upper('数据库登录用户名');”语句查询数据库表的数据类型。

方法:1、利用“LOWER(字段值)”将字段转为小写,或者利用“UPPER(字段值)”将字段转为大写;2、利用“REGEXP_LIKE(字符串,正则表达式,'i')”,当参数设置为“i”时,说明进行匹配不区分大小写。

方法:1、利用“alter system set sessions=修改后的数值 scope=spfile”语句修改session参数;2、修改参数之后利用“shutdown immediate – startup”语句重启服务器即可生效。


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