[20160126]建立loopback link问题.txt

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转载最新推荐文章于 2021-07-14 23:10:44 发布 · 82 阅读

本文详细解析了在Oracle数据库中配置Loopback link时遇到的问题及解决过程，包括监听配置、IP地址与主机名的区别及如何确保数据库链接正常工作。

[20160126]建立loopback link问题.txt

--今天为了测试的需要，我想建立loop link。执行如下：

SCOTT@book> @ &r/ver1

PORT_STRING VERSION BANNER
------------------------------ -------------- --------------------------------------------------------------------------------
x86_64/Linux 2.4.xx 11.2.0.4.0 Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production

CREATE PUBLIC DATABASE LINK loopback USING 'localhost:1521/book';

SCOTT@book> select * from dept@loopback;
select * from dept@loopback
*
ERROR at line 1:
ORA-12541: TNS:no listener

$ oerr ora 12541
12541, 00000, "TNS:no listener"
// *Cause: The connection request could not be completed because the listener
// is not running.
// *Action: Ensure that the supplied destination address matches one of
// the addresses used by the listener - compare the TNSNAMES.ORA entry with
// the appropriate LISTENER.ORA file (or TNSNAV.ORA if the connection is to
// go by way of an Interchange). Start the listener on the remote machine.

--奇怪给这么简单的问题给难住了。

$ rlsqlplus scott/book@127.0.0.1:1521/book
SQL*Plus: Release 11.2.0.4.0 Production on Tue Jan 26 09:19:33 2016
Copyright (c) 1982, 2013, Oracle. All rights reserved.
ERROR:
ORA-12541: TNS:no listener

$ rlsqlplus scott/book@192.168.100.78:1521/book
--通过。难道监听配置有什么问题吗？

$ netstat -tnlp | grep 1521
(Not all processes could be identified, non-owned process info
will not be shown, you would have to be root to see it all.)
tcp 0 0 192.168.100.78:1521 0.0.0.0:* LISTEN 24647/tnslsnr

--难道我要给在listener.ora加入127.0.0.1的IP吗? 试着加入看看：

LISTENER =
(DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 127.0.0.1)(PORT = 1521))
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.100.78)(PORT = 1521))
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
    )
)

ADR_BASE_LISTENER = /u01/app/oracle
DIAG_ADR_ENABLED_LISTENER=OFF

$ lsnrctl start

SYS@book> alter system register;
System altered.

$ rlsqlplus scott/book@127.0.0.1:1521/book
$ rlsqlplus scott/book@192.168.100.78:1521/book

--测试都可以通过。

SCOTT@book> select * from dept@loopback;
    DEPTNO DNAME          LOC
---------- -------------- -------------
        10 ACCOUNTING     NEW YORK
        20 RESEARCH       DALLAS
        30 SALES          CHICAGO
        40 OPERATIONS     BOSTON

--我对比别的机器发现在配置文件listener.ora 是写入主机名。设置修改主机名看看。

LISTENER =
(DESCRIPTION_LIST =
    (DESCRIPTION =
#      (ADDRESS = (PROTOCOL = TCP)(HOST = 127.0.0.1)(PORT = 1521))
#      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.100.78)(PORT = 1521))
      (ADDRESS = (PROTOCOL = TCP)(HOST = xxxxx)(PORT = 1521))
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
    )
)

ADR_BASE_LISTENER = /u01/app/oracle
DIAG_ADR_ENABLED_LISTENER=OFF

--再重新启动监听。

$ netstat -tnlp | grep 1521
(Not all processes could be identified, non-owned process info
will not be shown, you would have to be root to see it all.)
tcp 0 0 :::1521 :::* LISTEN 24817/tnslsnr

--可以发现这个时候监听在该主机的任何接口。测试上面的语句通过。
--从这里看出一些小细节。在监听指定IP，仅仅在特定的IP上监听。而如果使用主机名可以在该机器的任意IP上监听。

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