I’ve been away for the weekend, and have just checked the Drupal issue queue, and …
the Schema API patch got commited! Yay!

About a year back, I started to work on some functions to abstract table/field creation and alteration - first patch on May 13, 2006. It didn’t make it into Drupal 5, and I thought about all this some more, and other people did so, too.
I posted a first patch trying to implement an actual schema abstraction API on April 14, 2007, and soonafter realized that Barry Jaspan did basically the same with his Schema module. So, we then started to work together on this Schema patch, and I’ve to admit that it probably was this great collaboration that made it possible to get this first schema API into Drupal 6. Thanks again, Barry!

Now what does this buy us?

• Supporting more database engines, be it oracle, sqlite or mssql, becomes a lot easier.
• By now, only a minority of our contributed modules really support postgres, because of missing CREATE TABLE statements for pgsql. No more with this patch - we basically get postgres support for all of D6 contrib for free.
• update and install hooks are much simpler now
• there are many many more potential features that can be built upon this patch - Just to name a few, automatic database updates, a simple and consistent CRUD API, form scaffolding, simpler cck & views, schema-based data validation, etc. come to my mind (note: nothing of this is intended for drupal 6). For all this, this patch is a door opener.

There are already a few docs that might interest you

• API docs: http://api.drupal.org/api/HEAD/group/schemaapi
• Drupal.org handbooks: http://drupal.org/node/144765
• The Schema API group: http://groups.drupal.org/database-schema-api