I find the biggest thing to be vendor support for your applications. Many (maybe most?) application vendors try to keep their support down to the big ones Oracle, DB2 and MS SQL. You might find some support for Sybase as well. At my former employer a number of the developers used postgres and/or mysql for their development instances, but when it went to market you only had support for the big three. If you're using all in house applications it becomes a non-issue. Beyond that there are some very nice HA features that Oracle has that are desirable and are not matched in the FOSS world to my knowledge. 11g also has replaced the old *LOB data types with their Secure Files feature, some very cool stuff around encrypting, compression and de-duplication of data. These are all add on features to the core database and will cost you, so if you're not using them currently they don't factor in either. If you've got got a bunch of PL/SQL that you've developed, that would need to be migrated. Lastly, Oracle has a lot of fairly cool management tools that make life a lot easier for the DBA crowd. If they've been using these tools a lot you can expect considerable resistance from them regarding movement to a FOSS solution, they would need to develop an entirely new skill set and that almost always generates resistance. Josh Quoting Mike Miller <mbmiller at taxa.epi.umn.edu>: > We have a lot of data -- apparently about 9,000 tables in an RDBMS. It's > in Oracle now. As a fan of open source solutions, I would prefer to use > MySQL or other open source RDBMS, but at what cost? Before I even > consider moving data to MySQL from Oracle, I want to know what Oracle can > do that MySQL (or other FOSS product) cannot do. Have any of you studied > this or do you know of any reasonably serious comparative research or > reviews? Thanks. > > Mike >