This talk gives a good high level overview of the Facebook infrastructure: http://www.infoq.com/presentations/Scale-at-Facebook http://www.infoq.com/presentati

This talk gives a good high level overview of the Facebook infrastructure: http://www.infoq.com/presentations/Scale-at-Facebook http://www.infoq.com/presentations/Scale-at-Facebook In short they use sharded mysql instances (sans joins) as a key-value store with memcache on top of that.