[storm] Why doesn't Storm generate DDL?

[Free Ekanayaka]

Hey,

On Tue, Sep 10, 2013 at 11:00 PM, Jamu Kakar <jkakar at kakar.ca> wrote:
> I'm glad you're enjoying Storm!  We talked about this years ago and
> decided that there are at least two pieces:
>
> 1. Schema generation/initial creation of a schema for a new database.
> The method most of us have used is to always have a current schema.sql
> file that defines the schema for a project.  It should always be
> update and acts as documentation as well as bootstrapping for new
> deployments.
>
> 2. Patches to update live databases.  We have a simple system in
> storm.schema that can be used to apply patches to a live database and
> bring up to the spec defined in schema.sql.  There's the obvious
> problem that bugs in your patches can introduce skew between live
> production systems and what's in schema.sql but we've always lived
> with that and it hasn't been a big problem, in practice.

One solution would to initialize new databases using the patch
sequence, so the final schema will be always the same.

> We've always felt that schema generation, as in from Storm-based
> Python classes, was out of scope and instead always thought about
> annotating Storm properties in a way that would allow such a system to
> be built outside of Storm.  I still think that's a good idea.

Agreed. The main task with database schema is upgrading them, more
than creating, and the ideas in AutomaticSchemaGeneration don't seem
to really address that.

I believe that storm.schema is good enough and it's been successfully
used by a large and long-lived project like Canonical's Landscape.
There some documentation in the module docstring of
storm/schema/schema.py.

Cheers,

Free