There have been a few great blog posts recently from MySQL bloggers about Postgres, and vice versa, with good comments and follow-on from the real experts in both systems. I think this is wonderful. Learning how other databases solve hard problems is highly educational, especially because ACID databases face some of the hardest problems in computing. Making MySQL better is good for PostgreSQL. The reverse is just as true. And we should also be learning from SQLite, and CouchDB, and others who have overcome tough technical hurdles, built successful companies, created thriving and enthusiastic communities, or whatever their success has been.