An array in ruby has 3 methods that do the same thing.
length all return the number of items in an array.
An ActiveRecord::Relation however uses them a bit differently.
count is always going to run a query in the database while
size will return the number of items in the collection based on the objects currently in the object graph.
> songs = Songs.all > songs.size 10 > songs.count SELECT count(*) FROM songs; 10