Associations not using the right shard (possibly related to Kaminari)

[dvandersluis]

I'm not sure if this can be reproduced without kaminari, but it might be able to be. The following worked on 0.8.5 and does not on 0.9.2.

class User < ActiveRecord::Base
  has_many :posts
end

user = User.using(:shard1).find(id) # assume this returns a record with posts
user.posts.page(1).tap do
  # what I do in here doesn't really matter
end

On 0.8.5, this would run the following:

[Shard: shard1]  Post Load (2.0ms)  SELECT  "posts".* FROM "posts" WHERE "posts"."user_id" = $1 LIMIT 10
=> #<ActiveRecord::AssociationRelation [#<Post id: ...>]>

However, on 0.9.2:

[Shard: master]  Post Load (2.0ms)  SELECT  "posts".* FROM "posts" WHERE "posts"."user_id" = $1 LIMIT 10
=> []

Note how it's now using the wrong shard where it used to be using the right shard.

One work around I found is this:

user.posts.using(:shard1).page(1).tap { ... }

but this means I have to set the shard multiple times where I didn't used to have to. Therefore, updating to 0.9.2 broke working code.