 <p>Absolutely. For example, MySQL does not have hash and merge joins. Certain query patterns will suffer greatly there.</p> <p>The notion that the RDBMS used does not matter is strange to me. Different databases have very non-uniform performance characteristics. Performance very much varies with workload.</p> <p>If you want to exclude the RDBMS as much as possible from your tests you have to carefully make sure that you are not testing any RDBMS-specific performance features by accident. This is very hard.</p>