In the previous post, we took a brief look at some of the things we can learn from the queue manager using the DISPLAY command in runmqsc. It turns out that there is a lot of information available. So, what if we want to filter the results to see something more specific?

In WebSphere MQ version 6, the WHERE clause was introduced. This SQL-like expression allows an administrator to select a subset of results from the output of the DISPLAY command, based on the state of specific attributes. Users who have been using runmqsc for a long time, or who are new to the product, may not be aware of some of the things that are possible using this extended syntax.

The structure of the WHERE clause is WHERE(<attribute> <state> <value>) – for <state> we can substitute GT for Greater Than, LT for Less Than, EQ for Equals, and so on. You can find out more about the structure of the filter condition in the Infocenter.

In previous versions of WMQ, we could quickly find out how many messages were on a range of queue using DISPLAY QLOCAL(*) CURDEPTH. Unfortunately, that would show all of the queues. Of course, we could add a simple filter on part of the queue name to exclude the SYSTEM queues, using DIS QL(OURAPP.*). Now though, we can be a lot more specific. For example, to show all of the local queues whose depth is greater than 2, we could use WHERE(CURDEPTH GT 2):

dis ql(*) where (curdepth gt 2)
    34 : dis ql(*) where (curdepth gt 2)
AMQ8409: Display Queue details.
   QUEUE(SYSTEM.AUTH.DATA.QUEUE)           TYPE(QLOCAL)
   CURDEPTH(85)
AMQ8409: Display Queue details.
   QUEUE(SYSTEM.CLUSTER.REPOSITORY.QUEUE)
   TYPE(QLOCAL)                            CURDEPTH(45)
AMQ8409: Display Queue details.
   QUEUE(XML)                              TYPE(QLOCAL)
   CURDEPTH(3)

Now, what about the case were we want to know which of our channels are having problems. Which channels are currently in retry?

dis chs(*) where (status eq RETRYING)
    32 : dis chs(*) where (status eq RETRYING)
AMQ8417: Display Channel Status details.
   CHANNEL(TO.CLUSQM)                      CHLTYPE(CLUSSDR)
   CONNAME(localhost(1414))                CURRENT
   RQMNAME( )                              STATUS(RETRYING)
   SUBSTATE( )                             XMITQ(SYSTEM.CLUSTER.TRANSMIT.QUEUE)

How many times has this happened to you: messages are mysteriously “disappearing” from a particular queue, but you don’t know which application is reading from it. I actually came across this exact issue recently – a colleague was telling me that messages were vanishing from one of her queues, and we couldn’t explain what was consuming them.

Here’s a really handy command. We’ll analyse it afterwards.

dis conn(*) where (appltype eq USER) pid connopts appltag userid channel
    28 : dis conn(*) where (appltype eq USER) pid connopts appltag userid channel
AMQ8276: Display Connection details.
CONN(D4E4634620001002)
   EXTCONN(414D51434C4142325F514D2020202020)
   TYPE(CONN)
   PID(3784)
   APPLTAG(WebSphere MQ\bin\amqsput.exe)
   APPLTYPE(USER)                          CHANNEL( )
   CONNOPTS(MQCNO_SHARED_BINDING)          USERID(mqtester)

Let’s just review what we asked for here.

We’ve asked the queue manager to tell us about all (*) of the CONNections it knows about, WHERE the APPLTYPE [application type] is USER – this means that the results will exclude the MQ queue manager system processes like the channel initiator, the channel agent, the listener, and so on.

We’ve then limited the information displayed to show only the PID [process ID], CONNOPTS [MQ connection options], APPLTAG [name of the binary], USERID [user that the process is running under] and CHANNEL [channel that the application is connecting over, if applicable]. There are a bunch of other attributes on the CONN object, but are not relevant to our scenario.

Play around with the WHERE clause on DISPLAY. By combining the new queue manager objects in WebSphere MQ version 6 and filtering the results using WHERE, it is possible to troubleshoot much more quickly.

This is currently the last planned post in this very short series on runmqsc. If you have any handy commands that you use often, feel free to include them in the comments - we might run another entry in the future that lists some of the more interesting combinations.