Database Migration

• “If you don’t know the schema of your app, you don’t know your app” - Said one of our outside reviewers over lunch today
• ORM means we have to keep the database and the Objects “in sync”
• What happens if in release 2 I have to modify the database?

Migration

• When you discover you need a new column or table, you can modify the database
• E.g.break the “name” field into a “first name” and “last name”
• Data Migration
  • How do I move over all the user records that were already there?
• Logic Migration
  • What has to change in the server code to accomodate this change?
• Does this mean that migration is bad?
  • It’s not good nor bad: it’s unavoidable
  • It’s much more painful when you are ‘in production’