Updated DDL for SQL backend

[Benoit Gregoire]

> > Fair enough, it's fixed length.  But it will make for really ugly SQL for
> > JOINS, with the only benefit of saving four bytes.  I think using a
> > varbinary is much preferable (and just as portable).
>
> Or a varchar(32) and the hexstring...  Just as portable and actually
> human-readable (and human-enterable).   Not that I'm biased or anything
> ;)

I just didn't dare suggest it ;)