How to modify the processes value of oracle

alter system set processes=数值 scope=spfile;

select  b.MACHINE, b.PROGRAM, b.USERNAME, count(*) from v$process a, v$session b where a.ADDR = b.PADDR and  b.USERNAME is not null   
group by  b.MACHINE, b.PROGRAM, b.USERNAME order by count(*) desc

在 oracle中，要经常查看process:
查看ORACLE最大进程数：
SQL> select count(*) from v$session  #连接数
SQL> Select count(*) from v$session where status='ACTIVE'　#并发连接数
SQL> show parameter processes  #最大连接
SQL> alter system set processes = value scope = spfile;重启数据库  #修改连接
unix 1个用户session 对应一个操作系统 process
而 windows体现在线程
------------------------------------------------------------------------------
修改ORACLE最大进程数：
使用sys，以sysdba权限登录：
SQL> show parameter processes;
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes                      integer     1
db_writer_processes                  integer     1
job_queue_processes                  integer     10
log_archive_max_processes            integer     1
processes                            integer     150
SQL> alter system set processes=300 scope = spfile;
系统已更改。
SQL> show parameter processes;
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes                      integer     1
db_writer_processes                  integer     1
job_queue_processes                  integer     10
log_archive_max_processes            integer     1
processes                            integer     150
SQL> create pfile from spfile;
文件已创建。
重启数据库，
 SQL> show parameter processes;
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes                      integer     1
db_writer_processes                  integer     1
job_queue_processes                  integer     10
log_archive_max_processes            integer     1
processes                            integer     300
还有可以查询

select sessions_highwater  from v$license;

sessions_highwater 记录的是数据库会话曾经达到的最大值

查询数据库自启动以来最大的并发数量

select * from v$license

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;