memcached + MySQL solution was invented by livejournal.com and is using by facebook.com. So-called in-memory databases also in the market. And second important

memcached + MySQL solution was invented by livejournal.com and is using by facebook.com. So-called in-memory databases also in the market. And second important moment is the prices of RAM modules, SSDs and commodity hardware. In some cases it is better to create in-house solution that reflects your data structures and data flows.