There used to be a tremendous gap between these two databases. MySQL had an incredible dearth of features (subselects, triggers, TRANSACTIONS, and others were

There used to be a tremendous gap between these two databases. MySQL had an incredible dearth of features (subselects, triggers, TRANSACTIONS, and others were missing). PostgreSQL had the features, but it was relatively unpopular, so the language bindings were generally immature and not well documented. Then there was Interbase/Firebird, which was even less popular but was supposed to have an even better feature set (I never used it). These days, both have come a long way. MySQL has most of the necessary features, and PostgreSQL has perfectly good bindings in most popular languages. It doesn't matter so much which you use any more. The reputations remain, however, that MySQL is lacking critical features and that PostgreSQL is black magic. The legal issues around PostgreSQL are probably a little more stable at the moment, given the Oracle question (it now owns the trademarks). If Oracle starts causing any serious problems for MySQL, you can bet "YourSQL" will appear very quickly (sort of like how Iceweasel did). I wouldn't worry too much about it. Pick one, and start coding.