A well-designed schema in a properly-sized-and-tuned [MySQL, Postgres] instance can and will execute point lookups in a few hundred microseconds. That said, I

A well-designed schema in a properly-sized-and-tuned [MySQL, Postgres] instance can and will execute point lookups in a few hundred microseconds. That said, I agree that if you need a KV store, use a KV store. Though of course, Postgres can get you close out of the box with `CREATE UNLOGGED TABLE (data hstore);`.