Indicates whether a last agent can be selected when one is eligible to be selected during a commit operation. A last agent is eligible to be selected at the location that initiates a commit operation, and at locations that are selected as a last agent by the location that propagates the commit operation to that location.
Performance is usually enhanced when a last agent is selected because fewer interactions between this location and the last agent are required during a commit operation. However, if a communications failure occurs between a location and its last agent during a commit operation, the commit operation will not complete until resynchronization completes, regardless of the value of the Wait for outcome commitment option. Such a failure is rare, but this option allows the application developer to consider the negative impact of causing the user to wait indefinitely for the resynchronization to complete when such a failure occurs. This should be weighed against the performance enhancement that is provided by last agent optimization during successful commit operations. This consideration would generally be more significant for interactive jobs than for batch jobs.
There is one case where performance is not enhanced when a last agent is selected. If no committable changes have been made at an agent, and the Vote read only permitted commitment option has been set to Yes at that agent, then performance would actually be degraded by selecting that agent as a last agent. The decrease in performance occurs because fewer write operations to auxiliary storage are required when the vote read only optimization is used. Therefore, applications written such that no data is changed at all agents during most logical units of work should set the Last agent permitted option to No.
Possible values are:
System - The system is allowed to select a last agent at this location.
No - The system is not allowed to select a last agent at this location.
Note: The Last agent permitted commitment option cannot be changed to No if an API commitment resource that is specified to be called as the last agent has already been added to the commitment definition using the Add Commitment Resource (QTNADDCR) API.