1、查询用户连接
SELECT username, machine, program, status, COUNT (machine) AS 连接数量
FROM v$session
WHERE type<>'BACKGROUND'
GROUP BY username, machine, program, status
ORDER BY machine;
2、查询用户应用性能
SELECT osuser, a.username,cpu_time/executions/1000000||'s', sql_fulltext,machine
from v$session a, v$sqlarea b
where a.sql_address =b.address order by cpu_time/executions desc;
3、 修改最大连接数:
alter system set processes = 300 scope = spfile;
重启数据库 #修改连接
alter system set processes = value scope = spfile;
4、重启数据库:
shutdown immediate;
startup;
5、常用脚本
select count(*) from v$session;--查询oracle的连接数
select count(*) from v$session where status='ACTIVE';--查询oracle的并发连接数
select username,count(username) from v$session where username is not null group by username;--查看不同用户的连接数
select * from all_users;--查看所有用户：
--查看用户或角色系统权限(直接赋值给用户或角色的系统权限)：
select * from dba_sys_privs;
select * from user_sys_privs;
--查看角色(只能查看登陆用户拥有的角色)所包含的权限
select * from role_sys_privs;
--查看用户对象权限：
select * from dba_tab_privs;
select * from all_tab_privs;
select * from user_tab_privs;
--查看所有角色：
select * from dba_roles;
--查看用户或角色所拥有的角色：
select * from dba_role_privs;
select * from user_role_privs;
--查看哪些用户有sysdba或sysoper系统权限(查询时需要相应权限)
select * from V$PWFILE_USERS;
select count(*) from v$process --当前的连接数
select value from v$parameter where name = 'processes' --数据库允许的最大连接数