One trend I have observed but for which I have no hard data is that formally trained DBAs tend to prefer a proprietary RDBMS such as (most commonly) Oracle. I suspect that those with formal training and experience as a DBA (rather than as a software developer) tend to have a bias toward proprietary systems. In a larger environment with a defined role for a DBA (as opposed to a part-time consultant or someone doing double-duty as a developer), MySQL is likely to find less favor for this reason. Whether the scalability of MySQL is a real or imagined criticism becomes irrelevant at precisely this stage. Barring a strong reason to override this factor, when you have talented resources at your disposal, you want to give them the tools with which they are most comfortable and can get the most mileage. If your staff DBA with 15-plus years' experience wants Oracle and it's in the budget, do it; this approach always pays off in the long run.

There comes a point when comparing stable, mature, feature-rich products that one tends to stop obsessing about which one is "better" in an absolute sense. In place of this question is one that requires more insight: which one is more appropriate to a given situation. I think the leading RDBMSes have all reached this point now, including MySQL. The question of when this occurred may be open to some, and those few are welcome to conduct a debate on the matter. Suffice to say that this is the landscape of today, and with no slight to any of the leading systems, there are specific times to opt against the use of each. In the case of MySQL, I believe we've been able to cover some of the strongest ones—those that are not simply one version-release away from becoming outdated.

Now that you've read the reasons not to choose MySQL, be sure to read the alternate view: Five Compelling Reasons to Use MySQL.

Brent Toderash recently left the IT consulting firm of which he was an owner and manager to become a freelance writer, thinker, strategist and consultant. Founding editor of Penguinista.org, which he ran from 1999-2003, he lives in Winnipeg, Manitoba, blogs at toderash.net, guides several Web projects built on MySQL, and remains enough of a geek to have written this entire article in vi.