[jboss-user] [JBoss Messaging] - Re: Number of topic subscribers

timfox do-not-reply at jboss.com
Wed Dec 3 03:00:54 EST 2008

I'm not sure I agree with Clebert here.

Using multiple selectors on a single *queue* is generally considered an anti-pattern. This is because when a message is consumed the entire queue needs to be scanned to see if one matches.

However, using selectors on a *topic* is NOT considered an anti-pattern. Why? This is because the topic subscription will only accept messages that match the selector, therefore you know at consumption time that the subscription only contains matching messages and you don't need to scan anything.

This means selectors on a topic does not have the performance problems associated with selectors on queues.

Noelo - If you can explain your use case in more detail, that would be helpful.

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