Section 14.5. The Connection Concentrator

14.5. The Connection Concentrator

By default, each application is assigned a coordinator agent (MAX_CONNECTIONS = MAX_COORDAGENTS). Each agent operates within its own private memory and shares other memory sets with other agents. If an application connects to the database and does nothing, the resources associated with its coordinator agent are wasted. You can use the connection concentrator to avoid this.

The connection concentrator is enabled when MAX_CONNECTIONS is greater than MAX_COORDAGENTS. This means you can have more connections than the number of available coordinator agents. Each coordinator agent will service more than one connection.

When the connection concentrator is enabled, an application is in an active state only if there is a coordinator agent servicing it. Otherwise, the application is in an inactive state. Requests from an active application will be serviced by the database coordinator agent (and subagents in SMP or MPP configurations). Requests from an inactive application will be queued until a database coordinator agent is assigned to service the application (when the application becomes active). You can use the connection concentrator to control the load on the system.

For Internet applications with many relatively transient connections or any other applications with many relatively small transactions, the connection concentrator improves performance by allowing many more client applications to be connected. It also reduces system resource use for each connection.

When the connection concentrator is enabled, idle agents will always be returned to the idle agent pool, regardless of the value of the NUM_POOLAGENTS parameter. Therefore, more agents might be in the agent pool at any given time. Based on the system load and the time agents remain idle in the pool, agents might terminate themselves, as necessary, to reduce the size of the idle pool to the configured value.