gist.txt

Places
------
id



Comments
------
id
place_id





class: Place
database table: places

has_many :comments   -> place_id  -> Comment

has_many :white_games
has_many :black_games

def all_games
white_games + black_games
end

id   |  name
1    | Pizza
2    | Nom
3    | Nom
4    | nom


class: Comment
database table: comments


belongs_to :place   -> :place_id -> places.id -> Place

belongs_to :awesome_place, :foreign_key => :awesome_place_id, :class_name => 'Place'
belongs_to :terrible_place, :foreign_key => :terrible_place_id, :class_name => 'Place'


id  | awesome_place_id  | terrible_place_id
10  | 2                 | 5
11  | 2                 | 3
12  | 3                 | 4

c = Comment.last
c.awesome_place => look up by awesome_place_id




add_index :comments, [:awesome_place_id, :terrible_place_id]
add_index :comments, :terrible_place_id