Queue indexing (z/OS)

Receive queues on the target system should be created with an index to speed pruning of the queue after transactions are applied. You set the INDXTYPE parameter when you define a local queue.

The Q Apply program gets messages from the receive queue twice: once in first-in, first-out order for applying to the target table, and a second time to delete the message after it is applied. Because messages can be applied in a different order than they arrived on the queue, for the second MQGET operation at the receive queue the Q Apply program must look for the message by using its message identifier (MSGID).

A receive queue with INDXTYPE(MSGID) allows the queue manager to maintain an index of message identifiers that dramatically improves the speed at which the Q Apply program can prune receive queues. Otherwise, the program must search the queue sequentially.