Oracle连接配置解读

安装ORACLE数据库软件,dbca安装数据库后,需要配置listener连接数据库。这里有一些概念比较难理解,记录一些分析实战结论。

从连接端讲起。

1 连接数据库的方式

oracle的连接串有几部分构成,这里就按sqlplus为例,一个完成的连接串遵循下面格式

sqlplus 用户名/密码@主机:端口号/SID 可选as sysdba

下面先讲只有listener没有tns的情况

2 listener

使用listener连接需要配置完整连接信息,这里分为两种连接方式,我们看一个listener的例子:

(带sid的listener使用netmgr增加listener的datavase services即可出现sid的配置)

LISTENER2 =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = iZbp1d4tisi44j6vxze02fZ)(PORT = 1522))
  )
SID_LIST_LISTENER2 =
  (SID_LIST =
    (SID_DESC =
      (GLOBAL_DBNAME = gdn1400)
      (ORACLE_HOME = /fdisk1/oracle1400/base/dbhome_1)
      (SID_NAME = orcl1400)
    )
  )
ADR_BASE_LISTENER2 = /fdisk1/oracle1400/base

LISTENER1 =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = iZbp1d4tisi44j6vxze02fZ)(PORT = 1521))
  )
ADR_BASE_LISTENER1 = /fdisk1/oracle1400/base

这里有两个listener,有sid的叫做静态listener,没有sid的叫做动态listener。在查看状态时存在区别:

lsnrctl status listener1
...
Services Summary...
Service "orcl1400" has 1 instance(s).
  Instance "orcl1400", status READY, has 1 handler(s) for this service...
Service "orcl1400XDB" has 1 instance(s).
  Instance "orcl1400", status READY, has 1 handler(s) for this service...
The command completed successfully


lsnrctl status listener2
...
Services Summary...
Service "gdn1400" has 1 instance(s).
  Instance "orcl1400", status UNKNOWN, has 1 handler(s) for this service...
The command completed successfully

注意对于lsnrctl来说,service的名字是global database name

我们在看一个连接串:

sqlplus sys/password@iZbp1d4tisi44j6vxze02fZ:1521/orcl1400 as sysdba

这个连接串中最需要关注的就是服务名了,这里是orcl1400

注意!:这个服务名必须由listener中的某一个提供,这里listener2的服务名提供的是gdn1400,而listener1没有提供服务名。那么如何连接数据库呢?答案就是走listener1的连接会去数据库中动态的查询服务名(所以叫做动态连接)

SQL> show parameter service

NAME                     TYPE     VALUE
------------------------------------ ----------- ------------------------------
service_names                 string     orcl1400

也就是为什么使用orcl1400能连上数据库。这里我们使用静态连接试一下,也是可以连接数据库的(注意端口号和动态的不同)

sqlplus sys/password@iZbp1d4tisi44j6vxze02fZ:1522/gdn1400 as sysdba

SQL*Plus: Release 12.1.0.2.0 Production on Thu May 30 20:51:00 2019

Copyright (c) 1982, 2014, Oracle.  All rights reserved.


Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

SQL>

3 TNS

那么tns是什么呢?我们看下这个连接串。

sqlplus sys/password@iZbp1d4tisi44j6vxze02fZ:1521/orcl1400 as sysdba

@后面的信息很多,能否省略呢?比如

sqlplus sys/password@tns1400 as sysdba

这样看起来简洁很多也便于管理,TNS即实现了这个功能,我们看一个tnsnames.ora的配置:

NSN1522 =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = iZbp1d4tisi44j6vxze02fZ)(PORT = 1522))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = gdn1400)
    )
  )

NSN1521 =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = iZbp1d4tisi44j6vxze02fZ)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = orcl1400)
    )
  )

这里可以看到,最左面的NSN1522和NSN1521就是我们可以@的服务名字。内部的映射信息是指向listener的,这里的servicename要和上面的global database name对应上!

NSN1522, iZbp1d4tisi44j6vxze02fZ, 1522, gdn1400  -----> listener2
NSN1521, iZbp1d4tisi44j6vxze02fZ, 1521, orcl1400 -----> listener1

两个别名指向了两个不同的listener,连接测试:

# sqlplus sys/password@nsn1521 as sysdba

SQL*Plus: Release 12.1.0.2.0 Production on Thu May 30 20:58:51 2019

Copyright (c) 1982, 2014, Oracle.  All rights reserved.


Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

SQL>

# sqlplus sys/password@nsn1522 as sysdba

SQL*Plus: Release 12.1.0.2.0 Production on Thu May 30 20:58:55 2019

Copyright (c) 1982, 2014, Oracle.  All rights reserved.


Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

SQL>

注意:tns依赖lsnrctl使用,可以理解为hostname这样的概念,注意tns的SERVICE_NAME等信息必须和listener关联才能连接!

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