Diff and patch for schemas?

[krlmlr]

When the schema evolves, how do I apply the update to an existing database?

Use case: I have a script that creates the database from scratch, I've used it to create an instance and I have added data to that instance. Now the schema needs an update. Can I update the schema and keep the existing data in the database, and still have a comprehensive definition of the schema using the sqlr DSL?

Might be easier to achieve with #5.

Important cases:

• New column
• Renamed column
• New table
• Removed column (with warning)

Other cases:

• Splitting a table
• Changing semantics of a column (with a migration rule)