[gaius]

Google and Facebook aren't good examples, because they have no hard transactional requirements for their main applications. If a web page isn't included in one search result but is in the same search executed on a different node 5 minutes later, who would notice or care? If a status update gets dropped, it might be annoying, but you can always just resend it.

If you want to compare like for like, ask why Visa isn't using MongoDB for authorizations, or why American Airlines isn't using Redis for reservations.

[benblack]

So you are aware, yours is the traditional response. Somehow, doing what Google and Facebook do is "easy" because not everything requires transactions. This is false both because scale like that makes almost everything difficult, and because, as Google recently published, they are using transactions for their main application. NoSQL does not imply lack of transactions and transactions do not imply relational databases.

http://research.google.com/pubs/pub36726.html

"Databases do not meet the storage or throughput requirements of these tasks"

And Mongo or Redis? Come on, scro.

[gloob]

The post you are replying to does not contain the word "easy" at all, so far as I can discern. I think you might be attacking a straw man.