1、shared server和dedicated server连接方式比较
shared server 连接方式
dedicated server 连接方式
2、shared server process
在服务器上进行ps -ef| grep shared从而得到所有的oracle后台进程如下：
oracle 4476 1 0 19:18 ? 00:00:00 ora_pmon_shared oracle 4478 1 0 19:18 ? 00:00:00 ora_psp0_shared oracle 4480 1 0 19:18 ? 00:00:00 ora_mman_shared oracle 4482 1 0 19:18 ? 00:00:01 ora_dbw0_shared oracle 4484 1 0 19:18 ? 00:00:01 ora_lgwr_shared oracle 4486 1 0 19:18 ? 00:00:03 ora_ckpt_shared oracle 4488 1 0 19:18 ? 00:00:02 ora_smon_shared oracle 4490 1 0 19:18 ? 00:00:00 ora_reco_shared oracle 4492 1 0 19:18 ? 00:00:02 ora_cjq0_shared oracle 4494 1 0 19:18 ? 00:00:04 ora_mmon_shared oracle 4496 1 0 19:18 ? 00:00:00 ora_mmnl_shared oracle 4498 1 0 19:18 ? 00:00:00 ora_d000_shared oracle 4500 1 0 19:18 ? 00:00:00 ora_s000_shared oracle 4520 1 0 19:18 ? 00:00:00 ora_qmnc_shared oracle 4535 1 0 19:18 ? 00:00:00 ora_q002_shared oracle 4537 1 0 19:18 ? 00:00:00 ora_q003_shared oracle 15255 1 0 23:36 ? 00:00:00 ora_j000_shared
在客户端连接oracle数据库时，不会分配新的进程
客户端程序先连接到监听，然后监听程序通过调度器d000将任务放倒request Queue中，然后由空闲的共享进程s000来进行处理，处理完成之后把结果放倒response Queue中，然后调度器进程d000将结果返回给客户端程序
在服务器端用sqlplus连接的进程
oracle 16046 15677 0 May19 ? 00:00:01 oracleshared (DESCRIPTION=(LOCAL=YES)(ADDRESS= (PROTOCOL=beq)))
当在远程指定用DEDICATED方式连接时，也会分配一个单独的用户进程进行连接，如下
客户端的tnsnames.ora文件中，在connect_data中添加一行，(SERVER = DEDICATED)，从而指定用DEDICATED方式进行连接，连接的进程如下
oracle 16584 1 0 00:08 ? 00:00:00 oracleshared (LOCAL=NO)
2、dedicated server process
常见进程如下：
oracle 17596 1 0 00:37 ? 00:00:00 ora_pmon_dedicated oracle 17598 1 0 00:37 ? 00:00:00 ora_psp0_dedicated oracle 17600 1 0 00:37 ? 00:00:00 ora_mman_dedicated oracle 17602 1 0 00:37 ? 00:00:00 ora_dbw0_dedicated oracle 17604 1 0 00:37 ? 00:00:00 ora_lgwr_dedicated oracle 17606 1 0 00:37 ? 00:00:00 ora_ckpt_dedicated oracle 17608 1 0 00:37 ? 00:00:00 ora_smon_dedicated oracle 17610 1 0 00:37 ? 00:00:00 ora_reco_dedicated oracle 17612 1 0 00:37 ? 00:00:00 ora_cjq0_dedicated oracle 17614 1 0 00:37 ? 00:00:00 ora_mmon_dedicated oracle 17616 1 0 00:37 ? 00:00:00 ora_mmnl_dedicated oracle 17618 1 0 00:37 ? 00:00:00 ora_d000_dedicated oracle 17620 1 0 00:37 ? 00:00:00 ora_s000_dedicated oracle 17639 1 0 00:38 ? 00:00:00 ora_qmnc_dedicated oracle 17661 1 0 00:38 ? 00:00:00 ora_q001_dedicated oracle 17663 1 0 00:38 ? 00:00:00 ora_q002_dedicated oracle 18086 1 0 00:50 ? 00:00:00 ora_j000_dedicated客户端连接进去之后，服务器会给你分配一个新的进程，在不指定或者指定为dedicated连接方式之后，进程如下：
oracle 18194 1 1 00:52 ? 00:00:00 oraclededicated (LOCAL=NO)
服务器登陆连接进程如下：
oracle 18215 18214 1 00:53 ? 00:00:00 oraclededicated (DESCRIPTION=(LOCAL=YES)(ADDRESS=PROTOCOL=beq)))
当指定为shared方式连接dedicated server时，会出现如下错误：
C:\Users\Administrator>sqlplus system/orcl@dedicated SQL*Plus: Release 11.2.0.1.0 Production on 星期一 5月 20 15:56:47 2013 Copyright (c) 1982, 2010, Oracle. All rights reserved. ERROR: ORA-12520: TNS: 监听程序无法为请求的服务器类型找到可用的处理程序 请输入用户名:说明，如果服务连接方式为dedicated server，那么就不能使用shared server的连接方式来进行连接，但是如果是开启了shared server方式，那么还是可以使用dedicated server方式来进行连接的
小结论如下：
1. 如果是dedicated server，则客户端只能创建dedicated server connection
2. 如果是shared server，则客户端能创建dedicated server connection和shared server connection，只要在service name中指定server＝dedicated or server=shared.
（1）A dedicated server process, which services only one userprocess （2）A shared server process, which can service multiple userprocesses
SQL> show parameter dispatcher NAME TYPE ------------------------------------ ---------------------- VALUE ------------------------------ dispatchers string (PROTOCOL=TCP) max_dispatchers integer SQL> alter system set dispatchers = '' scope=both; System altered. SQL> show parameter shared_server NAME TYPE ------------------------------------ ---------------------- VALUE ------------------------------ max_shared_servers integer shared_server_sessions integer shared_servers integer 1 SQL> alter system set shared_servers = 0 scope=both; System altered
然后再查看数据库的进程的时候，就不会出现D000进程和S000进程了
为何创建的是专有模式的数据库,数据库却自动配置了dispatchers参数，暂时无解！！！！