Best way to list online users with PHP but without MySQL?

I want to make a script that will list online users when they enter a page. Simple way is record newly entered users into MySQL and list them for example every second. But I don't think it's a good idea with tons of users like in a facebook app come in and out of the page. There would be a way with Flash and PHP sockets but I really don't want to use Flash either. So is 开发者_C百科there any option left?

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Maybe you can use Memcache to store the users' information such as sessions for large amount of frequent query.I think it's an easy and effective way to do your job.

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Assuming you are using a login sistem so you have all the info you need stored somewhere in your database!

you can use sessions!

• http://php.net/manual/en/ref.session.php

here there is also a solution on stackoverflow

• Find Number of Open Sessions