While I was reading Jeremy Zawodny's reminder post on the Geek Dinner, I saw a link to David Sifry's post Zen and the Art of Bugfixing from March of last year. Tempted by the title, I followed the link and found an enjoyable post on David's bout with MySQL. I use Technorati at least once a day so I am a beneficiary of his bugfix. Cool.
IMHO, databases should be able to detect such problems and suggest changes. With performance profile expectations specified by the administrator, databases can easily isolate slow SQL commands and pull a list of suggestions.
If queries are expected to take no more than 1/2 second (which should be plenty for most use case) to execute, it doesn't take a rocket scientist to figure out that there is something wrong with queries that take more than 10 seconds to execute. Flagging those would give administrators better start at solving the problem than waiting for vague complaints from customers.
Heck, this would make a nice product addon for MySQL and I would be surprised if there isn't one out there already. [Don Park's Daily Habit]