DB2 Version 10.1 for Linux, UNIX, and Windows

TOTALSCMEMBERCONNECTIONS threshold

The TOTALSCMEMBERCONNECTIONS threshold specifies the maximum number of concurrent database connections on a coordinator member for a service superclass.

Type: Aggregate
Definition domain: Service superclass
Enforcement scope: Member
Tracked work: Connections
Queuing: Yes
Unit: Number of concurrent connections in service class
Predictive or reactive: Predictive

When the TOTALSCMEMBERCONNECTIONS threshold in the service class is reached, subsequent coordinator connections that join the service superclass are queued until the specified queue size is reached. By default, the queue size is zero, which means that no connections can be queued. If a connection joins the queue of a TOTALSCMEMBERCONNECTIONS threshold, the connection is considered to be in a transient state.

Note: If a threshold action of CONTINUE is specified for a queuing threshold, it effectively makes the size of the queue unbounded, regardless of any hard value specified for the queue size.

Tracked connections include both new client connections and existing client connections that switch to the service class from another service class. Connections switch service classes by associating with a different workload definition that is mapped to a different service class. Workload reevaluation occurs only at transaction boundaries, so connections can switch service classes only at transaction boundaries; however, because resources that are associated with WITH HOLD cursors are maintained across transaction boundaries, connections with open WITH HOLD cursors cannot switch service superclasses. When the connection concentrator is on, any application that is switched leaves the service class. When the application is switched in at the subsequent statement, it must rejoin the service class and consequently pass the threshold.

When the queue size threshold is reached, the threshold action is triggered. The TOTALSCMEMBERCONNECTIONS threshold controls only coordinator connections. Connections made by subagents are not counted towards the threshold.

If you set a threshold value for TOTALMEMBERCONNECTIONS, set it large enough to accommodate the threshold that you specify for TOTALSCMEMBERCONNECTIONS. For example, if you define five service superclasses for a database and each of them has a TOTALSCMEMBERCONNECTIONS threshold value of 10, the TOTALMEMBERCONNECTIONS threshold value should be at least 50.