JBossDeveloper

Well, the JMS spec is explicit in that should never rely on the results of a QueueBrowser to accurately represent the contents of a queue, anyway. Any application that does that is broken:

Section 5.9, JMS 1.1 spec:

"Messages may be arriving and expiring while the scan is done. JMS does not
require the content of an enumeration to be a static snapshot of queue content.
Whether these changes are visible or not depends on the JMS provider."

Regarding selectors: Let's say your server is running in 100MiB of RAM, so you set paging max size to 70MiB (for example), and you have 10 TiB (terabytes) of messages, most paged to storage.

You have a selector that only selects certain messages, and you expect all matching messages to be consumed irrespective of whether they are paged or not.

Think about what you're asking here.

Either

a) We store all 10 TiB in memory and apply selectors as normal in memory? Clearly we can't do that since we only have 100MiB of RAM

b) Somehow, we scan through the files on disk, perhaps applying indexes and efficiently fetch all matching messages?

Hang on a second, that's exactly what a relational database is designed to do, not a messaging system! We're not in the business of writing a RDBMS.

This kind of thing comes up from time to time. If you're using a messaging system to select subgroups of messages from a very large dataset (bigger than can fit in RAM) then probably you shouldn't be using a messaging system, you should be using a database.

You're effectively just executing queries against tables and then is not the primary purpose of a messaging system.

And I very doubt that would work efficiently in Websphere MQ either.

If you use a screwdriver as a hammer it might work, but a hammer would work better.

If you don't want to page, you can set the AddressFullMessagePolicy to BLOCK instead of PAGE, this will push back on producers preventing them from sending more than can fit in memory.

That's an alternative to paging.

Take a look in the user manual.

You can either PAGE, BLOCK or DROP when an address is full. It's up to you how you configure it.