20.1 Functionality for connection pool clustering

This section describes the connection pool clustering functionality.

The following table describes the organization of this section.

Table 20‒1: Organization of this section (Connection pool clustering functionality )
Category	Title	Reference location
Description	Connecting to Oracle using Oracle RAC	20.1.1
	Overview of connection pool clustering	20.1.2
	Resource adapters used	20.1.3
	Connection pool clustering operations	20.1.4
	Procedure for stopping or starting a connection pool manually	20.1.5
Settings	Settings required for clustering a connection pool	20.1.6

Note:: There is no specific description of Implementation and Operations for this functionality.

The connection pool clustering functionality optimizes the operations in a system where the database is used in a cluster configuration. You can use this functionality when you connect to Oracle using Oracle RAC. By using the connection pool clustering functionality, you can prevent the drop in system availability during errors and during maintenance. The following points describe the operations when an error occurs in the database node and when maintenance is performed for the database node while you are using the connection pool clustering functionality.

When an error occurs in the database node

When a connection cannot be obtained, such as during an OS, hardware, or software error, you can automatically suspend the connection pool connected to the database node where the error occurred (auto-suspension functionality). Even when a connection request is sent from the J2EE application to the resource adapter, no connection request is sent to the suspended connection pool, so the processing is not cancelled until a TCP/IP timeout occurs. This enables the J2EE application to continue business by obtaining a connection from a connection pool connected to another normal database node.

Also, when the database node error is recovered, you can automatically restart the connection pool (auto-restart functionality). If the connection pool is restarted, the automatically recovered database node is accessed again, so you need not execute the cjclearpool command to delete the connection pool for recovering the database node.
When maintenance is performed for the database node

When you perform maintenance for a database node, you can use commands to suspend the member connection pool at any time (manual suspension functionality). Due to this, you can separate that database node and perform maintenance.

Also, when you restart the database node after maintenance finishes, you can use commands to restart the connection pool at any time (manual restart functionality).

Note that in the connection pool clustering functionality, when a failure is detected while a connection is being obtained, the connection will be obtained from another normal member resource adapter. At this time, no error occurs in the application.

This section describes how to connect to Oracle clustered by using the Oracle RAC functionality, and the features and functionality of a connection pool when the connection pool is clustered (connection pool clustering).

Organization of this section

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