From an interview with a Facebook engineer working on a new distributed DBMS
Q: What problem are you most passionate about solving right now?
A: As a part of my commitment to solving scale problems, I'm currently writing a distributed SQL database. I think traditional databases have already come up with a great way to abstract data access in SQL, but the context of old implementations has been single-machine based. Very few of these databases have done a nice job scaling up to handle very large amounts of data. In addition, not all databases have different ways to handle data with different access patterns, which results in inefficiency. My new database is trying to address these issues. I'm very passionate about this project because I think I'm getting a head-start on something that people will have to deal with soon.