The MySQL documentation impresses me. I can’t recall a time when I didn’t find what I was looking for or that its details were lacking. Documenting a database server is difficult; the amount of information to organize and communicate clearly is staggering. I tasted that challenge when I helped update the Drizzle documentation, which was recently updated online.
I think Drizzle will become be a serious alternative or compliment to MySQL. Imho, Drizzle was until now held back by its documentation, or lack thereof, which created an insurmountable stumbling block for even clever DBAs. For example, Drizzle is largely comprised of plugins, but none of those plugins were documented until now.
I use the MySQL documentation as a goal, that to which the Drizzle documentation strives, not necessarily in style but in completeness. Although Drizzle began life as a fork of MySQL, it has evolved to the point where its own success will be, imho, largely dependent upon the completeness of its own documentation.