I'm sure this is not a new topic -- I've read mention of it elsewhere
-- but in addition to :joins => :profile, Active Record also
needs :inner_joins => :profile, :outer_joins => :profile, :left_joins
=> :profile, and all the popular combinations of join types.
I've got a sqlite development environment with mysql in production.
mysql says "what?" when it see LEFT OUTER JOIN.
I'm going to try playing with database specific code through the
ActiveRecord::Base.instanceof? method, but that certainly isn't a
particularly elegant approach.