In a recent presentation the Continuent folks claim that they support "daylight maintenance" or online schema upgrades. See Clustering for the Masses: A Gentle Introduction to Tungsten for MySQL, especially pages 22-28.

Is anyone using Tungsten for MySQL in this way? It sounds too good to be true.

I also wonder if the Community Edition supports all of the features discussed in the presentation. They say elsewhere that it is not crippleware but in their own productization table "Zero downtime upgrade" appears to only be available in the more advanced versions. So I'm skeptical. Community support seems rather non-existent so a commercial license with support is probably warranted (they do not disclose pricing). I have not contacted them directly yet as I prefer community vetting but this solution, despite its value proposition and power to make an admin's life easier just doesn't seem to get the kind of attention it might warrant.

If not Tungsten for MySQL, how do you handle online schema upgrades? MySQL Cluster (NDBENGINE) is not well-suited to web applications.

Cheers