http://blog.csdn.net/xiaoyao6650/article/details/4027041
查看processes
#当前的连接数
select count(*) from v$process;
#数据库允许的连接数
select value from v$parameter where name = ‘processes‘;
#查看连接配置信息
show parameter processes;
#修改连接数
alter system set processes = [value] scope = spfile;
例子：
alter system set processes = 300 scope = spfile;
查看session
#查看当前有哪些用户正在使用数据
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;
#会话数
select count(*) from v$session;
#查看会话配置信息
show parameter session;
#并发会话数
select count(*) from v$session where status=‘ACTIVE‘;
#修改会话数
alter system set session= [value] scope = spfile;
例子：
alter system set session= 300 scope = spfile;
重启数据库
shutdown immediate;
startup;
查看v$session, v$process数量
#v$session s, v$process p 的查看
select s.username,count(*) from v$session s, v$process p where s.paddr=p.addr group by s.username;
#包含关于当前活动进程的信息
V$PROCESS;
#使用describe查看表结构，可以看到比较详尽的描述
describe v$session;
describe v$process;
V$session 和V$process信息描述文档-http://www.cnblogs.com/xd502djj/archive/2012/07/10/2585005.html