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As far as data transofmration goes you have two options:

1. Something akin to ActiveMigration is RubyOnRails world. This allows going back and forth different versions of your data's schema.

2. Use a more open data scheme such as Google App Engine uses where adding/removing properties to an object is not as disruptive compared to SQL-based solutions.

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It turns out the system works fine with SQL based alters. We do have to do real work to deploy expensive alters (apply them to standbys, fail over, repeat, or worse) but in general it's cheap to change schemas.

Unfortunately, it's very manually intensive to roll back schema changes, so it's one of the few places where we put old school process in place (a DBA who reviews all schema changes prior to deployment)

Did you look at ActiveMigration? Even though I never used ruby/ror I found it a very sensible approach to thinking about schema evolution.

ActiveMigration really solves a different problem. Our problem is that adding indexes or altering popular tables is impossible to do on a live and in production database. To get those changes out we have to go through quite a bit of extra work. It's really a MySQL limitation, not a process problem.

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