If you want to use the database session failover functionality, set a timeout in database (for HiRDB, UAP processing time monitoring functionality).

If the database session failover functionality is enabled, table records of the database that are targeted for operation during functionality processing, are exclusively controlled. As a result, when problems such as a failure on a J2EE server host occur, records targeted for operation might remain in exclusion state. In this case, creation of new HTTP sessions or connection between J2EE servers and database might fail.

If you set a timeout, such situations are detected, the transaction is rolled back, and you return to the state before records are exclusively controlled when a timeout occurs. Therefore, there is no impact on the system.

For preventing malfunctioning, set a timeout value for the database that is greater than the timeout value set in DB Connector. For details on database settings and procedure, see the uCosminexus Application Server HiRDB UAP Development Guide when using HiRDB and Oracle manuals when using Oracle.

The following table describes the processing in which records are exclusively controlled, tables targeted for operation in the processing, impact on the system when a failure occurs on a J2EE server during a processing, and the messages are output.

Table 6-46 Processing in which records are exclusively controlled and impact on the system when a failure occurs on a J2EE server during a processing

Sr. No.	Processing that exclusively controls records	Table targeted for operation	Impact on the system when a failure occurs	Output message
1	Negotiation processing when starting a Web application	Application information table	Because application negotiation fails, the Web application that uses the database session failover functionality fails to start.	Not output
2	Processing of creating global session information	Blank record information table	The system can only create a total of 90% of the HTTP sessions. After this, HTTP session creation or deletion processing might fail.	When integrity mode is disabled: KDJE34368-W When integrity mode is enabled: KDJE34312-W
3	Processing of deleting global session information	Blank record information table	The system can only create a total of 90% of the HTTP sessions. After this, HTTP session creation or deletion processing might fail.	When integrity mode is disabled: KDJE34377-E When integrity mode is enabled: KDJE34312-W
4	Processing of updating global session information	Session information storage table	The number of HTTP sessions that you can create in the system reduces by one. After this, if you receive a request that operates the reduced HTTP session, HTTP session acquisition fails.	When integrity mode is disabled: KDJE34368-W When integrity mode is enabled: KDJE34312-W
5	Processing of monitoring validity of global session information	Application information table	Validity of global session information in the database is not monitored.	When integrity mode is disabled: Do not execute exclusion processing When integrity mode is enabled: KDJE34336-W