Virtual host scalability

[zellster]

Hello,

I am in the position where I need to support 1-2 million virtual hosts. The obvious way to handle this in lsws (or Apache) I am guessing, is to throw everything into one huge XML config file. Given that approach, what type of algorithmic lookup behavior (O(n), O(1), etc.) is used internally for Host: --> vhost mapping? At what point can I expect the vhost mapping to not scale?

Any suggestions appreciated.