oracle closes connection

Oracle closed connection

When using Oracle database, many users often encounter the problem of connection timeout or connection being closed. Understanding the principles and common problems of Oracle database connections can help users better handle these problems and improve the efficiency of database operation. This article will introduce the closing and reconnecting of Oracle database connections.

Causes of connection closure

In Oracle database, there are many factors that may cause the connection to be closed. Here are some common reasons:

1. Network failure: If a network failure causes the connection between the client and the database server to be interrupted, the connection will be closed. In this case, the client will receive a network error or connection timeout error message.
2. Client abnormal termination: If the client application terminates abnormally, the connection will also be closed. In this case, the client receives an operating system crash or application crash error message.
3. Server failure: If the database server encounters a failure, such as hardware failure or network failure, the connection will also be closed. In this case, the client will receive a database error or ORA error message.
4. Connection idle timeout: If there is no activity on the connection for a period of time, the connection will be closed. In this case, the client will receive a connection timeout or ORA error message.

The impact of connection closure on the database

When the connection is closed, the impact on the database depends on how the connection is closed. If the connection is closed gracefully, the database will not be significantly affected, except that the connection will be removed from the database's active connections. If the connection is closed abnormally, it may cause some problems in the database, such as deadlock or blocking.

Methods to close the connection

In Oracle database, there are several ways to close the connection:

1. Client application operation: The client application can pass Call the API or directly send the command to close the connection to close the connection. This method is useful for applications that need to close connections promptly.
2. Database Administrator Action: The database administrator can manually close the connection by connecting to the database server and using SQL tools. This method is useful for database administrators who need to check for and close idle connections.
3. Automatic closing: Oracle database has a mechanism to automatically close connections. This feature can be enabled by configuring database parameters. This approach is useful for reducing idle connections and freeing up resources.

Configuration of automatic closing parameters

In Oracle database, you can enable the mechanism of automatic closing of connections by modifying the parameter configuration of the database. The following are some commonly used auto-close parameters:

1. SQLNET.EXPIRE_TIME: This parameter specifies how long the connection can exist in an idle state. If this time is exceeded, the connection will be closed. The default value is 0, which disables the automatic closing of connections.
2. SQLNET.INBOUND_CONNECT_TIMEOUT: This parameter specifies the maximum waiting time for the connection. If the connection is not established within the specified time, the connection will be closed. The default value is 60 seconds.
3. INBOUND_CONNECT_TIMEOUT_listener_name: This parameter specifies the maximum waiting time of the listener. If the listener does not process the request within the specified time after receiving it, the connection will be closed.
4. DEAD_CONNECT_DETECT_INTERVAL: This parameter specifies the time interval for the database to detect dead connections. The default value is 10 seconds.

Method of reconnecting

When the Oracle database connection is closed, you need to reconnect to the database. Here are some common ways to reconnect:

1. Restart the application: When the connection is closed, the application can be restarted to create a new connection.
2. Re-establish the connection using the same connection parameters: If the connection parameters did not change when the connection was closed, the client application can re-establish the connection using the same connection parameters.
3. Change connection parameters and re-establish the connection: If the connection parameters change when the connection is closed, the client application must change the connection parameters in order to re-establish the connection.
4. Restart the database server: If the database server encounters a failure, such as a hardware failure, the server needs to be restarted to restore the database service. After the server is restarted, client applications can reconnect to the database using the same connection parameters.

Summary

The closing of Oracle database connections is a common problem, and dealing with connection closures is one of the skills that database managers and developers need to master. Understanding the principles and common problems of Oracle database connections can help users better handle these problems and improve the efficiency of database operation. It is recommended that users regularly check idle connections to avoid problems such as connection timeout or connection being closed.

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