Better advice: just use Postgres.

Three reasons: 1) your data is probably relational, even if you think it's not, 2) if you have non-relational records, Postgres has JSON and hash storage types that perform better than most NoSQL databases, and 3) The architecture, standards compliance, and sheer capabilities of Postgres are all best in class. Seriously, if you want to read some good C, peruse the PostgreSQL source. Go Bears.

Unless you're trying to do some analytics (in which case, find a column store), or want to use it and forget it (Amazon's database services; and RDS is Postgres), Postgres is the way to go.