HardenGetBackout (10-digit signed integer)
Whether to maintain an accurate backout count.
Local Model Alias Remote Cluster Y Y For each message, a count is kept of the number of times that the message is retrieved by an MQGET call within a unit of work, and that unit of work subsequently backed out. This count is available in the MDBOC field in the message descriptor after the MQGET call has completed.
The message backout count survives restarts of the queue manager. However, to ensure that the count is accurate, information has to be "hardened" (recorded on disk or other permanent storage device) each time a message is retrieved by an MQGET call within a unit of work for this queue. If this is not done, and a failure of the queue manager occurs together with backout of the MQGET call, the count may or may not be incremented.
Hardening information for each MQGET call within a unit of work, however, imposes a performance overhead, and the HardenGetBackout attribute should be set to QABH only if it is essential that the count is accurate.
- On i5/OS, the message backout count is always hardened, regardless of the setting of this attribute.
The following values are possible:
- QABH
- Backout count remembered.
Hardening is used to ensure that the backout count for messages on this queue is accurate.
- QABNH
- Backout count may not be remembered.
Hardening is not used to ensure that the backout count for messages on this queue is accurate. The count may therefore be lower than it should be.
To determine the value of this attribute, use the IAHGB selector with the MQINQ call.