This parameter determines the maximum number of asynchrony table queues (ATQs) in the access plan that the federated server supports. The mechanism of ATQs does not work in DB2® pureScale® environments.
When ANY or -1 is specified, the optimizer determines the number of ATQs for the access plan. The optimizer assigns an ATQ to all eligible SHIP or remote pushdown operators in the plan. The value that is specified for DB2_MAX_ASYNC_REQUESTS_PER_QUERY server option limits the number of asynchronous requests.
If the special register or the bind option do not override the federated_async configuration parameter, the value of the parameter determines the maximum number of ATQs in the access plan that the federated server allows. If the special register or the bind option overrides this parameter, the value of the special register or the bind option determines the maximum number of ATQs in the plan.
Any changes to the federated_async configuration parameter affect dynamic statements as soon as the current unit of work commits. Subsequent dynamic statements recognize the new value automatically. A restart of the federated database is not needed. Embedded SQL packages are not invalidated nor implicitly rebound when the value of the federated_async configuration parameter changes.
If you want the new value of the federated_async configuration parameter to affect static SQL statements, you need to rebind the package.