Even modest db work usually involves concurrency. Mongo locks. Postgres rocks. [1] 1: http://www.postgresql.org/docs/current/static/mvcc-intro.html http://www

Even modest db work usually involves concurrency. Mongo locks. Postgres rocks. [1] 1: http://www.postgresql.org/docs/current/static/mvcc-intro.html http://www.postgresql.org/docs/current/static/mvcc-intro.htm...