ORACLE之报错TNS-03505

1、问题描述
同一服务器，K-DB连接ORACLE，创建dblink后，在k-db中使用dblink连接查询oracle中的表报错。如下，

TBR-12130: Unable to connect to remote database(link_name=LN_SCOTT).   
TBR-130092:(ORA-12154) TNS:could not resolve the connect identifier specified

然后，在kdb用户下tnsping test，发现报错如下，

TNS Ping Utility for Linux: Version 11.2.0.1.0 - Production on 18-FEB-2021 17:28:32
Copyright (c) 1997, 2009, Oracle.  All rights reserved.
Used parameter files:
TNS-03505: Failed to resolve name

但是，使用oracle用户tnsping test，没有问题。

TNS Ping Utility for Linux: Version 11.2.0.1.0 - Production on 18-FEB-2021 17:14:08
Copyright (c) 1997, 2009, Oracle.  All rights reserved.
Used parameter files:
Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = ora11g)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = test)))
OK (0 msec)

2、问题原因
经查，kdb用户无法tnsping test原因是没有tnsnames.ora文件的权限

3、处理方法
使用oracle用户修改tnsnames.ora文件的权限

total 16
-rw-r--r-- 1 oracle oinstall  315 Jan  1 09:55 listener.ora
drwxr-xr-x 2 oracle oinstall 4096 Jan  1 09:47 samples
-rw-r--r-- 1 oracle oinstall  187 May  7  2007 shrept.lst
-rw-r----- 1 oracle oinstall  323 Jan  1 10:04 tnsnames.ora
[oracle@ora11g admin]$ chmod 755 tnsnames.ora

修改完权限后，kdb用户即可tnsping test成功，且dblink可用。

TNS Ping Utility for Linux: Version 11.2.0.1.0 - Production on 18-FEB-2021 17:31:19
Copyright (c) 1997, 2009, Oracle.  All rights reserved.
Used parameter files:
Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = ora11g)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = test)))
OK (0 msec)

[kdb@ora11g config]$ kdsql sys/kdb
kdSQL 11  
Connected to Inspur K-DB.
SQL> select * from dept@ln_scott;
    DEPTNO DNAME          LOC          
---------- -------------- -------------
        10 ACCOUNTING     NEW YORK
        20 RESEARCH       DALLAS
        30 SALES          CHICAGO
        40 OPERATIONS     BOSTON
4 rows selected.
SQL> exit

注：k-db连接oracle创建dblink方式，此文档略。