PHP long polling, without excessive database access
<p>I've always enjoyed the idea of long polling; on my development server I've played with various notification / new post systems, each using javascript to hold a connection and 'wait' for some sort of response. I've always had an issue with many implementations of this, they all involve repetitively polling the mySQL server to check for new rows.</p>

<p>A dedicated server for long polling requests is a possibility, but it seems very wasteful to continuously poll (around ever 3 seconds seems common) a database server for every client. Its a huge waste of resources for something that is relatively insignificant. </p>

<p>Is there a batter way? </p>
