Managing the Dead Message Queue

You can use the Message Queue Command utility (imqcmd) to manage the dead message queue as you manage other queues, with some differences. For example, because the dead message queue is system-created, you cannot create, pause, or destroy it. Also, as shown in Table 6–3, default values for the dead message queue sometimes differ from those of normal queues.

Dead Message Queue Properties

You configure the dead message queue as you configure other queues, but certain physical destination properties do not apply or have different default values. Table 6–3 lists queue properties that the dead message queue handles in a unique way.

Table 6–3 Dead Message Queue Treatment of Standard Physical Destination Properties

Property	Unique Treatment by Dead Message Queue
limitBehavior	The default value for the dead message queue is REMOVE_OLDEST. (The default value for other queues is REJECT_NEWEST.) Flow control is not supported on the dead message queue.
localDeliveryPreferred	Does not apply to the dead message queue.
maxNumMsgs	The default value for the dead message queue is 1000. The default value for other queues is -1 (unlimited).
maxNumProducers	Does not apply to the dead message queue.
maxTotalMsgBytes	The default value for the dead message queue is 10 MB. The default value for other queues is -1 (unlimited).
isLocalOnly	In a broker cluster, a dead message queue is always a global physical destination and this property is permanently set to false.

Message Contents

A broker can place an entire message on the dead message queue, or it can discard the message body contents, retaining just the header and property data. By default, the dead message queue stores entire messages.

If you want to reduce the size of the dead message queue and if you do not plan to restore dead messages, consider setting the imq.destination.DMQ.truncateBody broker property to true:

imqcmd update bkr -o imq.destination.DMQ.truncateBody=true

This will discard the message body and retain only the headers and property data.