Use the queue's index
Supported only on WebSphere MQ for z/OS.
When you browse an indexed queue that contains only messages of a single priority (either persistent or nonpersistent or both), the queue manager performs the browse by making use of the index, when any of the following forms of browse are used:
- If the queue is indexed by MSGID, and the above condition is true, browse requests that pass a MSGID in the MQMD structure are processed using the index to find the target message.
- If the queue is indexed by CORRELID, and the above condition is true, browse requests that pass a CORRELID in the MQMD structure are processed using the index to find the target message.
- If the queue is indexed by GROUPID, and the above condition is true, browse requests that pass a GROUPID in the MQMD structure are processed using the index to find the target message.
If the browse request does not pass a MSGID, CORRELID, or GROUPID in the MQMD structure, the queue is indexed, and a message is returned, the index entry for the message must be found, and information within it used to update the browse cursor. If you use a wide selection of index values, this extra processing adds little overhead to the browse request.
Parent topic:
The browse cursor
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