Yet another opinion about proprietary vs open source databases
Although a little bit advertising, the blog entry of Jignesh Shah points to an interesting fact: You can easily spend hundred times the server price for the database license. The business case to use a proprietary database should be a really good one. There are still companies out there, who use databases like DB2 or Oracle for all data because they did it so for the last 10 years. Opensource RDBMS like Postgres or Mysql may have not all functions of an Oracle, but you should ask yourself: Is this advantage really big enough to justify 40.000$ or 15.000$ per core? In my humble opinion this price tag justifies a dual database strategy.