ORACLE调优基础知识

Sql代码
1.select count(*) from v$process 
select count(*) from v$process --当前的数据库连接数
2.
Sql代码
1.select value from v$parameter where name = 'processes'
select value from v$parameter where name = 'processes'--数据库允许的最大连接数
3.
Sql代码
1.alter system set processes = 300 scope = spfile;
alter system set processes = 300 scope = spfile;--修改最大连接数:
4.
Sql代码
1.shutdown immediate; 
2.startup;
shutdown immediate;
startup;--重启数据库
5.
Sql代码
1.SELECT osuser, a.username,cpu_time/executions/1000000||'s', b.sql_text,machine  
2.from v$session a, v$sqlarea b 
3.where a.sql_address =b.address order by cpu_time/executions desc;
SELECT osuser, a.username,cpu_time/executions/1000000||'s', b.sql_text,machine
from v$session a, v$sqlarea b
where a.sql_address =b.address order by cpu_time/executions desc;
--查看当前有哪些用户正在使用数据
6.
Sql代码
1.select count(*) from v$session 
select count(*) from v$session   --当前的session连接数
7.
Sql代码
1.select count(*) from v$session where status='ACTIVE'
select count(*) from v$session where status='ACTIVE'　--并发连接数
8.
Sql代码
1.show parameter processes 
show parameter processes   --最大连接
9.
Sql代码
1.alter system set processes = value scope = spfile;