Add support for Materialized Views

[jayadevanm]

The documentation does mention that Views are not supported. It looks like Materialized Views are also not supported, though they are more like tables than views. We can create indexes, they contain data etc.

[bplunkett-stripe]

It's unfortunately not the straight forward (think webs of dependencies), but I do intend to add support for them and have a mental model in my head as to how I will achieve it. I first would like to refactor the SQL generation a bit before I implement (materialized) views.

[KEHyeon]

@bplunkett-stripe I wonder when the View will be added.
and I'm very interested in this project. Can I try refactoring it too?

[bplunkett-stripe]

Sure! You can give it a shot, but a thorough implementation will be pretty complex. I can try to add really simple view support in the future.

[KEHyeon]

@bplunkett-stripe
First, I want to analyze this project code. Can you briefly explain the code and internal principles?

[bplunkett-stripe]

There are three main parts:

1. Schema extraction
2. Schema diffing
3. SQL generation

The latter part is the most complex: we take the diff generated from step 2 and build a graph that we topologically sort in order to get our ordered SQL statements