This group of metrics gives you the availability and status of the managed database. Metrics include:Database Status、Da
This group of metrics gives you the availability and status of the managed database. Metrics include:Database Status、Database Process Check、aximum # of sessions since startup and Availability. 在Oracle10G中引入了metric,,用来监控数据库表空间,如下实例:
1、确认现有的metric
SQL> conn / as sysdba
已连接。
SQL> select count(1) from dba_thresholds;
COUNT(1)
----------
22
2、创建表空间
SQL> select metric_id,metric_name from v$metricname where metric_name like'%space%'
2 ;
METRIC_ID METRIC_NAME
---------- ----------------------------------------------------------------
9001 Tablespace Bytes Space Usage
9000 Tablespace Space Usage
SQL> create tablespace tbs_lw datafile '/opt/oracle/oradata/charge/tbs_lw01.dbf' size 10m;
表空间已创建。
3、创建新的metric
SQL> BEGIN dbms_server_alert.set_threshold (dbms_server_alert.tablespace_pct_full,NULL, NULL, NULL, NULL, 1, 1, NULL, dbms_server_alert.object_type_tablespace, 'TBS_LW');END;
2 /
PL/SQL 过程已成功完成。
4、查看新创建的metric
SQL> select count(1) from dba_thresholds;
COUNT(1)
----------
23
SQL> SELECT warning_value, critical_value, status FROM dba_thresholds WHERE metrics_name = 'Tablespace Space Usage' AND object_name = 'TBS_LW';
WARNING_VALUE CRITICAL_VALUE STATUS
-------------------- -------------------- -------
80 95 VALID
5、模拟一个表数据增长达到threshold
SQL> create table t1 tablespace tbs_lw as select * from user_objects;
表已创建。
SQL> select count(*) from t1;
COUNT(*)
----------
30060
SQL> insert into t1 select * from t1 where rownum
已创建4000行。
SQL> insert into t1 select * from t1 where rownum
已创建4000行。
SQL> commit;
提交完成。
6、查看是否生效
SQL> SELECT reason, message_level,DECODE(message_level, 5, 'WARNING', 1, 'CRITICAL') ALERT_LEVEL FROM dba_outstanding_alerts WHERE object_name = 'TBS_LW';
REASON MESSAGE_LEVEL ALERT_LE
-------------------------------------------------- ------------- --------
表空间 [TBS_LW] 已占用 [90 Percent] 5 WARNING
7、停用metric
SQL> BEGIN dbms_server_alert.set_threshold (dbms_server_alert.tablespace_pct_full,dbms_server_alert.operator_do_not_check, '0',dbms_server_alert.operator_do_not_check, '0', 1, 1, NULL,dbms_server_alert.object_type_tablespace, 'TBS_LW');END;
2 /
PL/SQL 过程已成功完成。
SQL> SELECT warning_value, critical_value, status FROM dba_thresholds WHERE metrics_name = 'Tablespace Space Usage' AND object_name = 'TBS_LW';
WARNING_VALUE CRITICAL_VALUE STATUS
-------------------- -------------------- -------
0 0 VALID
8、取消metric
BEGIN dbms_server_alert.set_threshold (dbms_server_alert.tablespace_pct_full,NULL, NULL, NULL, NULL, 1, 1, NULL, dbms_server_alert.object_type_tablespace, 'TBS_LW');END;
2 /
PL/SQL 过程已成功完成。
SQL> SELECT warning_value, critical_value, status FROM dba_thresholds WHERE metrics_name = 'Tablespace Space Usage' AND object_name = 'TBS_LW';
未选定行

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。

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。

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“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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