What should I do if Oracle does not have a listener?

Oracle has no listener solution: 1. Confirm whether the listener configuration is correct and ensure that the name and port number of the listener matches the database instance; 2. Use the lsnrctl command to start the listener; 3. Use the lsnrctl command to check The status of the listener; 4. Use the alter command to register the database instance to the listener; 5. Check the firewall settings on the server to ensure that access to the listener port is allowed; 6. Check whether the network connection is normal; 7. View the listener log file to find any error or warning messages; 8. Seek professional support.

#The operating environment of this article: Windows 10 system, oracle11g version, Dell G3 computer.

When the Oracle database does not have a listener, it cannot connect to the database instance through the network. In this case, we need to take some steps to solve the problem.

Here are some possible solutions:

Check the listener configuration:First, we need to confirm that the listener configuration is correct. This can be checked by editing the listener configuration file and ensuring that the listener matches the name and port number of the database instance. Typically, the listener configuration file is located in the listener.ora file in the ORACLE_HOME/network/admin directory.

Start the listener: If the listener is not running, we need to start it. You can use the lsnrctl command to start the listener. First, we need to log into the server on the operating system and run the command prompt or terminal with administrator rights. Then, start the listener using the following command:

lsnrctl start

If the listener is already running, we can try to restart it:

lsnrctl stop
lsnrctl start

This will stop the listener and restart it.

Check the listener status: You can check the status of the listener using the following command:

lsnrctl status

If the listener is already running, but cannot connect to the database instance, it may exist Other issues, such as network failure or the database instance not registering correctly with the listener.

Register database instance: If the database instance is not correctly registered to the listener, we need to register it manually. A database instance can be registered with a listener using the following command:

alter system register;

This will force the database instance to register with the listener.

Check the firewall settings: Another possible cause is that the firewall settings are blocking access to the listener port. We need to check the firewall settings on the server and make sure access to the listener port is allowed.

Check the network connection: You can also check whether the network connection is normal. You can try using the ping command to test the availability of the server and the telnet command to test the connectivity of the listener port. If you can't ping the server or telnet to the listener port, you may have a network connection problem.

Check the log file: If none of the above steps solve the problem, we can check the listener log file for more information. The listener log file is usually located in the listener.log file in the ORACLE_HOME/network/log directory. You can review this file for any error or warning messages.

Seek professional support: Finally, if we cannot solve the problem, you can contact Oracle support or a professional database administrator for help. They will be able to provide more professional support and solutions.

In short, when the Oracle database does not have a listener, we need to check the listener configuration, start the listener, register the database instance, check the firewall settings, check the network connection, view the log file, and seek professional support if necessary to solve the problem.

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