Thanks for the article. It's always good to read the open opinions of others and freely debate them .. sort of like the scientific community :D
I agree on your point about query plans; they do cost a hell of a lot. This is one of the reasons why we use caching solutions such as Redis and Memcached on top of a well planned out relational databases that we can poke and prod with SQL.
Bret Taylor of FriendFeed/Facebook fame implemented a scalable system schema free system on top of MySQL where he could attach thin tables arbitrarily to JSON collections as the index. When migrations happened the collections would be scanned and the tables rebuilt. Digg has done similar work, but no open source project ever made the light of day. This schema free system powered most of the site (one true datastore).
After cracking open Redis and then looking at mysql-sr-lib it brought that FriendFeed idea back full circle. Basically I think mysql-sr-lib 2.0 could be a 1:1 implementation of Redis functions implemented as MySQL stored procedures. The only adaptation I would make is that functions would be namespaced (a table per namespace) so that collections could be made. It would be up to the client to decide how to take advantage of namespacing. Do use it for functional collections or sharding for example? Clients would also have to use a distribution strategy to map keys to a namespace/collection. The idea is a lot clearer in my mind now thanks to making the mysql-sr-lib discovery.
I agree on your point about query plans; they do cost a hell of a lot. This is one of the reasons why we use caching solutions such as Redis and Memcached on top of a well planned out relational databases that we can poke and prod with SQL.
What's the hook for MySQL you are talking about?