We were recently asked how to clear a queue of all messages within one of our tools.
In this post we cover how to do this using MQGem tools as several of them offer this capability. Open up the twisty for each tool to read how to do this.
Using MO71
There are two options for clearing a queue of all messages when using MO71. One directly interacts with the messages in a Message List dialog, and the other uses the Clear Queue command via the command server. The latter can fail if someone else has the queue open.
MO71: Using the Message List dialog
In MO71 you can browse a list of messages on a queue, then in the context menu of that dialog choose Message Selection → Apply to all Messages. Then press the Delete All button, or select Delete All from the right-mouse button context menu and all the messages will be deleted.
Delete all messages using MO71
Take care when deleting messages from a production queue manager. Consider that it might be safer to Move the message(s) to a separate holding queue, just in case the message proves to be important after all. MO71 makes it simple to Move messages too. Just fill in the holding queue name, and then press the Move All, rather than Delete All, button.
MO71: Using the Clear Queue command
From a Queue List dialog in MO71, you can choose to clear a queue from the context menu. As a destructive command, this will show a confirmation dialog before it goes ahead.
Delete all messages using the Clear command in MO71
Remember that this command can fail if the queue is open by another application at the time.
Using the Q program
You can use the Q program to quickly destructively get off all the messages on a queue, to ensure it is empty before you begin using it for something else. This can work even when the queue is in use (unless it is exclusively in use of course) and the CLEAR QLOCAL command can’t be used.
Here is an example which destructively gets (-I) from Q1 and uses a zero-length buffer and accepts that the messages will be truncated (-=t0):-
q -m MQG1 -I Q1 -=t0
Take care when deleting messages from a production queue manager. Consider that it might be safer to Move the messages to a separate holding queue, just in case they prove to be important after all. This is simple to achieve using a command like the following:
q -m MQG1 -I Q1 -o HOLDING.Q
Using QLOAD
You can use QLOAD to quickly destructively get off all the messages on a queue, to ensure it is empty before you begin using it for something else. This can work even when the queue is in use (unless it is exclusively in use of course) and the CLEAR QLOCAL command can’t be used.
Here is an example which destructively gets (-I) from Q1 and discards them (-f null), aka sends them to the null file destination:-
qload -m MQG1 -I Q1 -f null
Take care when deleting messages from a production queue manager. We would recommend using QLOAD to actually move the messages to an output file, in case you change your mind about deleting them!
qload -m MQG1 -I Q1 -f c:\temp\Q1deletedmsgs.qld
Using MQEdit
In MQEdit you can browse a list of messages on a queue, then in the context menu of that dialog choose Message Operations → Apply to all Messages. Then press the Delete All button, or select Delete All from the right-mouse button context menu and all the messages will be deleted.
Delete all messages using MQEdit
Take care when deleting messages from a production queue manager. Consider that it might be safer to Move the message(s) to a separate holding queue, just in case the message proves to be important after all. MQEdit makes it simple to Move messages too. Just fill in the holding queue name, and then press the Move All, rather than Delete All, button, or simply Drag and Drop the messages onto the new queue.
Using MQSCX
You can of course issue the MQSC CLEAR QLOCAL(q-name) command from MQSCX. However, it can go one better than this. The CLEAR QLOCAL command is problematic because it can fail when someone else has the queue open, even if it is not open in a way that stops you getting messages. Instead you can issue the following command in MQSCX:-
=clear qlocal(Q1)
then MQSCX will first attempt the CLEAR QLOCAL command and if that fails with "object in use" then it will switch to getting the messages off the queue instead. You can read more about this in MQSCX: Clearly a better way.
If you don't have any of these tools, but would like to try any or all of them out, please contact support@mqgem.com and a 1-month trial licence will be sent to you with no obligation to buy. You can download the tools from our website.
MQGem Software 