PH58747: SHARED QUEUE SEARCH ENHANCEMENT FOR MQGET WITH MATCH OPTIONS.

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• When getting a message from a shared queue with match options,
  MQ must use CF facilities to search for an appropriate message
  to satisfy the MQGET.
  
  This can be an time-consuming process and there are different
  strategies which could be used to minimise the time taken. The
  cost depends on the depth of the queue, the number of
  messages matching the requirements and where those messages are
  on the queue.
  
  MQ uses a combination of strategies which works well for most
  use cases. However, in some cases this can be inefficient.
  
  This APAR will enhance the search logic to allow greater control
  of the search strategy in circumstances where the default
  strategy is not appropriate.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of IBM MQ for z/OS Version 9       *
  *                 Release 2 Modification 0, Release 3          *
  *                 Modification 0 and Release 4 Modification 0. *
  ****************************************************************
  * PROBLEM DESCRIPTION: When getting a message from a shared    *
  *                      queue with match options, the most      *
  *                      efficient searching logic varies        *
  *                      depending on queue depth, number of     *
  *                      messages matching the search and        *
  *                      message location on the queue.          *
  ****************************************************************
  In some scenarios with high queue depth and a particular
  distribution of messages with matching IDs, finding the
  appropriate message for each MQGET request can require a very
  large amount of work for MQ and Coupling Facility code.
  

Problem conclusion

• This APAR introduces a control to allow the behaviour of the
  search logic to be altered. Under the guidance of IBM Support,
  such alterations may be of benefit for diagnostic purposes or to
  allow MQ to resolve specific problem scenarios more efficiently.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UI98327 UI98328 UI98329

Modules/Macros

• CSQEMGEF CSQESTRT CSQIRECP
  

Fix information

• Fixed component name

  IBM MQ Z/OS V9

• Fixed component ID

  5655MQ900

Applicable component levels

• R200 PSY UI98329

     UP24/09/25 P F409  

• R300 PSY UI98328

     UP24/09/25 P F409  

• R400 PSY UI98327

     UP24/09/25 P F409  

Fix is available

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