>>>Does the fact that MySql is released with the GNU license mean our product must be open source also?
>>>
>>>Any suggestions and warnings regading MySql use?
>>
>>http://www.mysql.com/about/legal/licensing/oem/
>>
>>The FAQs are useful e.g. http://www.gnu.org/licenses/gpl-faq.html#GPLInProprietarySystem
>
>I read that as "as long as they can be upgraded independently", i.e. the end user can load a newer version of MySql without even telling you, then it's surely separate.

That's one way to look at it. If you can upgrade components separately, and nothing breaks, then they're definitely independent.

But, it's possible they could be upgraded separately, but something could break - DB schema or WHY. In some people's minds that might imply a hard link of some kind.

To my mind the most important phrase of the FAQ is "However, in many cases you can distribute the GPL-covered software alongside your proprietary system. To do this validly, you must make sure that the free and non-free programs communicate at arms length [emphasis mine], that they are not combined in a way that would make them effectively a single program.". I think it's pretty clear that an RDBMS like MySQL is inherently designed to communicate at arm's-length. As long as you communicate with it through its (industry?)-standard APIs I don't see a problem.