利用Oracle清理无效会话（oracle删除会话）

【参考范文】

Oracle provides the Alter System command to clean invalid sessions. Invalid sessions include any program that has been disconnected from the database while the session remains connected. Such sessions can cause strange performance problems, such as a slow application.

There are three parts to cleaning up the invalid sessions in Oracle. First, we will use the following command to list all the active sessions:

SELECT sid, serial#, username, program, osuser, status

FROM v$session

WHERE status = ‘ACTIVE’;

Second, we need to identify the session that caused the performance issue. To do this, we can use the following code to check the log files:

SELECT event, waits, secs_in_wait

FROM v$session_wait

WHERE sid = sidval;

Lastly, to get rid of an idle session, we can use the following command:

ALTER SYSTEM KILL SESSION ‘sidval, serial#’;

Where sidval and serial# are the identified session ID and serial number of the session that is causing problems. After running this query, the session will be removed from the database.

In situations where performance issues persist longer than usual, we can also use the Alter System command in Oracle to drop all the invalid sessions in the database. To do this, we can use the following command:

ALTER SYSTEM DISCONNECT SESSION;

It is important to remember that the Alter System command is a powerful and dangerous one. Make sure you always use the command with the correct syntax, and with the correct parameters. Otherwise, you risk corrupting or damaging your database.

In conclusion, invalid sessions in Oracle can cause performance issues, such as slow application response times. The Alter System command can be used to identify and remove such sessions from the database. It is important to use this command with caution, as improper usage can cause serious damage to the database.