Database Link

What DB Link Can and Cannot Do

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Can and Cannot For better understanding the features of a database link which may play an important role in data migration, we should study what a database link can and cannot do in a distributed database system in order to develop our data migration strategy. Generally speaking, you can perform Data Query Language (DQL) and […]
SQLNET

How to Resolve TNS-12545: Connect failed because target host or object does not exist

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TNS-12545 Let’s see how we reproduce TNS-12545. C:\Users\ed>tnsping compdb TNS Ping Utility for 64-bit Windows: Version 12.1.0.1.0 – Production on 21-JUL-2014 19:10:59 Copyright (c) 1997, 2013, Oracle.  All rights reserved. Used parameter files: C:\oracle\app\client\ed\product\12.1.0\client_1\network\admin\sqlnet.ora Used TNSNAMES adapter to resolve the alias Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = primary01)(PORT = 1521)) […]
SQLNET

How to Resolve TNS-03505: Failed to resolve name

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TNS-03505 Failing to resolve TNS names could involve any one of the network configuration files, such as tnsnames.ora or sqlnet.ora. There’re several possible causes may throw TNS-03505: Absent Local Naming Connect Identifier Mismatch Search for Wrong Domain 1. Absent Local Naming There’re several naming methods supported by Oracle in sqlnet.ora. Only local naming can be […]
DNS

sqlplus, tnsping or lsnrctl Hangs

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sqlplus, tnsping or lsnrctl Hangs I can’t cover all situations in this post, but I have some cases that can share with you. Those hanging all point to one problem: Domain name resolution. Does the database server use DNS to do name resolution? Sometimes, DNS traps the name resolution in an unknown and indefinite loop […]
Listener

TNSPING – 8 Aspects You Should Know

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tnsping tnsping is a utility provided by Oracle to test the listener is available or not from clients. If there’s any problem in the path to the destination, it will fail with different aspects. Here I list several possible error types below for your reference. “tnsping is not recognized as an internal or external command” […]
TNS Name

How to Implement Transparent Application Failover (TAF) by Local Naming

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General backgroundBesides Connect-Time Failover by local naming, there is a function Transparent Application Failover (TAF) can do Run-Time Failover to enable user to continue his work transparently when connection failed over to other database (listener).There are two types of Run-Time Failover method, both methods are suitable for RAC architecture, but not for Data Guard, because […]