oracle closed connection

Oracle database is one of the most popular relational databases in the world and has been widely used due to its stability, security and scalability. But in the actual operation and maintenance process, sometimes we encounter connection problems with the Oracle database. The specific manifestation is that the connection cannot be opened normally or it cannot work properly after the connection. At this time, we need to do some troubleshooting and processing to solve this problem.

1. The connection cannot be opened normally

1. Network failure

Fundamentally speaking, the Oracle database connection is a connection based on network protocols. If there is a problem with the network connection, it may cause the connection to fail. For example, if the network does not have sufficient bandwidth or capacity, the connection may time out or be refused.

Solution:

(1) Ensure network availability and stability.

(2) Check whether the network connection configuration, such as IP address, port, etc., is correct.

(3) If there is security software such as firewall or anti-virus software, you need to ensure that these software will not block the Oracle database connection.

2. Oracle database service failure

If the Oracle database service fails, the connection will also fail. Possible reasons include the service not starting, the service crashing, or a disk error, etc.

Solution:

(1) First check the status of the Oracle database instance. You can check whether the Oracle database listener has been started by executing the command sqlplus /nolog.

(2) If the Oracle database service has not been started, you need to start the service first and then try to connect to the database.

(3) If the Oracle database service has been started but still cannot be connected, you need to check the service log to determine the cause of the failure.

2. It cannot work normally after connecting.

1. Account or permission issues

If you cannot execute any command after successful connection, it may be because there is no correct Permissions or roles.

Solution:

(1) Check whether the connected user has the permission to execute the required command.

(2) Check whether authorized objects, such as tables, views or functions, etc. exist.

(3) Check whether the connected user has been disabled or locked.

2. Database configuration issues

If the SQL query or DML operation cannot be performed normally after the connection is successful, or an exception occurs during the connection process, it may be caused by a database configuration issue.

Solution:

(1) Check the status of the database configuration parameters and ensure that they are consistent with the requirements of the application or client.

(2) Determine the cause of the problem by accessing the logs, warnings or error messages of the database.

(3) Check whether the operating system parameters related to the database, such as disk space, memory and CPU, are normal.

3. Summary

The above lists the common reasons that may cause Oracle database connection failure. They may be intertwined or they may be separate reasons. For these problems, we can troubleshoot and solve them one by one to restore the normal working status of the database connection.

In the actual operation and maintenance process, we need to establish complete monitoring and alarm capabilities, as well as strategies for quickly discovering and solving problems. This can reduce losses caused by connection failures and improve our work efficiency.

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