Home

 

HardenGetBackout (MQLONG)

Local	Model	Alias	Remote	Cluster
Yes	Yes	No	No	No

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 BackoutCount 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 that an MQGET call retrieves a message within a unit of work for this queue. If this is not done, the queue manager fails, and the MQGET call backs out, the count might or might not be incremented.

Hardening information for each MQGET call within a unit of work, however, imposes a performance overhead, so set the HardenGetBackout attribute to MQQA_BACKOUT_HARDENED only if it is essential that the count is accurate.

On i5/OS, UNIX systems, and Windows, the message backout count is always hardened, regardless of the setting of this attribute.

The following values are possible:

MQQA_BACKOUT_HARDENED

Hardening is used to ensure that the backout count for messages on this queue is accurate.

MQQA_BACKOUT_NOT_HARDENED

Hardening is not used to ensure that the backout count for messages on this queue is accurate. The count might therefore be lower than it should be.

To determine the value of this attribute, use the MQIA_HARDEN_GET_BACKOUT selector with the MQINQ call.

 

Home