Demonstrates that update_all behavior is different between mysql and the other databases

gistfile1.txt

# Activate the gem you are reporting the issue against.
gem 'activerecord', '4.0.2'
gem 'pg'
require 'active_record'
require 'minitest/autorun'
require 'logger'

ActiveRecord::Base.establish_connection(adapter: 'postgresql', username: 'user', password: 'pass', database: 'test')
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :posts do |t|
    t.integer :author_id
    t.string :author_stuff
  end

  create_table :authors do |t|
    t.string :stuff
  end
end

class Post < ActiveRecord::Base
  belongs_to :author
end

class Author < ActiveRecord::Base
end

class BugTest < Minitest::Unit::TestCase
  def test_update_all
    Post.joins(:author).update_all('author_stuff = authors.stuff')
  end
end