I don't think so. I'm sure anything older than a year on FB goes on some sort of extra-slow storage, which is likely why their search is crap and will forever be crap.

The real expense for FB is likely to be in guaranteeing realtime sync between dozens of platforms and gazillions of clients. All that JS and PHP has to be coded up and served somehow...

Same for Twitter -- everyone remembers the "whale" when they were struggling with infrastructure pains, then they massively invested to sort that out... and ended up chasing profits to pay for it all, of course.

Snapchat will soon get there as well.