Type of index

 

Only supported in WebSphere MQ for z/OS.

The queue attribute, IndexType, specifies the type of index that the queue manager maintains in order to increase the speed of MQGET operations on the queue.

You have five options:

Value Description
NONE No index is maintained. Use this when messages are retrieved sequentially (see Priority).
MSGID An index of message identifiers is maintained. Use this when messages are retrieved using the MsgId field as a selection criterion on the MQGET call (see Getting a particular message).
MSGTOKEN An index of message tokens is maintained. Use this when messages are retrieved using the MsgToken field as a selection criterion on the MQGET call (see WebSphere MQ Workflow).
CORRELID An index of correlation identifiers is maintained. Use this when messages are retrieved using the CorrelId field as a selection criterion on the MQGET call (see Getting a particular message).

Notes:

  1. If you are indexing using the MSGID option or CORRELID option, set the relative MsgId or CorrelId parameters in the MQMD. It is not beneficial to set both.

  2. Browse uses the index mechanism to find a message if a queue matches all of the following conditions:

    • It has index type MSGID, CORRELID, or GROUPID

    • It is browsed with the same type of id

    • It has messages of only one priority

  3. Avoid queues (indexed by MsgId or CorrelId) containing thousands of messages because this affects restart time. (This does not apply to nonpersistent messages as they are deleted at restart.)

  4. MSGTOKEN is used to define queues managed by the z/OS workload manager.

For a full description of the IndexType attribute, see WebSphere MQ Application Programming Reference. For conditions needed to change the IndexType attribute, see WebSphere MQ Script (MQSC) Command Reference.

 

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IBM is a trademark of the IBM Corporation in the United States, other countries, or both.