ActiveRecord::QueryMethods#limitとActiveRecord::FinderMethods#take ref: http://qiita.com/Naggi-Goishi/items/856a7698f167efdb2a17

file0.rb

twelves = User.where(age: 12)

# ActiveRecord::QueryMethods#limitを使用する
twelves.limit(3)
# User Load (4.9ms)  SELECT  `users`.* FROM `users` WHERE `users`.`age` = '12' LIMIT 3
#=> <#ActiveRecord::Relation [<#User id: 1, name: "ゴン＝フリークス", age: 12>, <#User id: 2, name: "キルア＝ゾルディック", age: 12>, <#User id: 3, name: "ピーター・パン", age: 12>]>

# ActiveRecord::FinderMethods#takeを使用する
twelves.take(3)
#=> [<#User id: 1, name: "ゴン＝フリークス", age: 12>, <#User id: 2, name: "キルア＝ゾルディック", age: 12>, <#User id: 3, name: "ピーター・パン", age: 12>]

file1.rb

twelves.limit(3).class
# => User::ActiveRecord_Relation

twelves.take(3).class
# => Array

file2.rb

User.where(age: 12).take(3)

file3.txt

User Load (4.9ms)  SELECT  `users`.* FROM `users` WHERE `users`.`age` = '12' 

file4.txt

User Load (4.9ms)  SELECT  `users`.* FROM `users` WHERE `users`.`age` = '12' LIMIT 3

file5.rb

twelves = User.where(age: 12).limit(3)
twelves = twelves.limit(5)

file6.rb

twelves = User.where(age: 12).limit(3)

file7.txt

User Load (4.9ms)  SELECT  `users`.* FROM `users` WHERE `users`.`age` = '12' LIMIT 3

file8.rb

twelves = twelves.limit(5)

file9.txt

User Load (4.9ms)  SELECT  `users`.* FROM `users` WHERE `users`.`age` = '12' LIMIT 5