Materialized Views for sqlalchemy-redshift

[ewengillies]

I will be creating a DDLElement that can support Redshift's CREATE MATERIALIZED VIEW with table attributes, noteably sortkeys and distkeys/styles.

Todos

• Factored out and tested table_attributes parser
• Write the CreateMaterializedView DDLElement
• Write the DDL compiler
• Test on redshift db

Default Todos

• MIT compatible
• Unit Tests
• Documentation
• Updated CHANGES.rst

Notes:

• I made the table_attributes parser less permissive to match expected outcomes from Redshift. I'm happy to relax this and delegate the error messages to Redshift, but it could be nice to catch them early. Up to the maintainers.
• It looked like the same parsing code wanted to allow Columns in additions to strings (and iterables thereof) to be allowed to specify keys. I added the checked needed in if this is the case.
• I took the liberty of making a new module ddl, since the Create and Drop queries are normally treated somewhat differently than Executable or ClauseElement. This was just an observation of mind, i'm happy to move it all into commands.
• Unfortunately REFRESH MATERIALIZED VIEWS is a command. So my contribution is a little split between these two modules, perhaps awkwardly. Happy to take advice here.
• Finally, I made some changes to the doc folder to reflect the new module. I haven't used Sphinx so much, but it all seemed pretty self explanatory. Even so, I'm not sure how to generate the docs to check locally. Please advise, thanks!

[ewengillies]

@jklukas , here is the MR we discussed on #201 . Awaiting your review, no rush tho! Thanks :)

[jklukas]

This overall looks great and integration tests are passing, so the refactoring involved looks correct. I left a few nits to fix and otherwise this should be ready to merge.

[jklukas]

I just posted a new release 0.7.9 which includes this change.