When to use MySQL vs PgSQL?
mdasen: Use a good abstraction library and start coding.  Seriously.PostgreSQL tends to be what is favored by people here.  I used to use it for everything until I tried to set up a replicated cluster with it.  PostgreSQL's replication is severely lacking.  Slony-I, the most mature of the bunch, is very difficult to set up (with many steps needed for every single table) and a lot slower than MySQL's replication (due to its use of SQL and triggers rather than binary log shipping as well as the fact that its design causes communication costs to grow quadratically).However, PostgreSQL's query planner is a lot better than MySQL's (especially if you're doing something like subqueries) and I find that complex queries run decently faster.  The community process is also a lot more attractive.To address the Oracle question:Oracle cannot withdraw InnoDB.  It's GPL licensed.  Anyone can fork it should Oracle decide they don't want to play ball - just as anyone can fork MySQL.  In fact, there are already forks underway including Drizzle.  So, that isn't a big deal.  The bigger deal would be if Oracle decided to halt future development.  I'm guessing they won't since it would simply mean they would loose control to the community that still has rights to the GPL'd code.In the end, don't worry about this issue.  It distracts from what is really important: actually creating something.  They both work fine.  There are plenty of abstractions that will allow you to create code that will work with either with no modifications.  Do that, build your application, and let the pundits from either side debate this issue until they're blue in the face while you're actually creating useful things.