如何測試在Rails控制檯中添加索引性能？

我想喲測量添加索引的性能。

，比如我有如下表：

create_table "classifications", :force => true do |t| 
    t.integer "app_id" 
    t.integer "user_id" 
    t.integer "topic_id" 
    t.string "targit_type" 
    t.integer "targit_id" 
    t.datetime "created_at" 
    t.datetime "updated_at" 
end

我想在這裏添加三個指標：

# Classification 
add_index :classifications, :app_id, name: "index_classifications_on_app_id" 
add_index :classifications, :user_id, name: "index_classifications_on_user_id" 
add_index :classifications, [:target_id, :targit_type], name: "index_classifications_on_targit_id_and_targit_type"

所以我想測量這種變化的表現。

如何才能做到這一點？我應該在Rails控制檯中這樣做嗎？

>> Agreement.find_by_user_id_and_review_id(User.last.id, Review.last.id)                    
    User Load (14.2ms) SELECT "users".* FROM "users" ORDER BY "users"."id" DESC LIMIT 1 
    Review Load (4.5ms) SELECT "reviews".* FROM "reviews" ORDER BY "reviews"."id" DESC LIMIT 1 
    Agreement Load (2.2ms) SELECT "agreements".* FROM "agreements" WHERE "agreements"."user_id" = 2064 AND "agreements"."review_id" = 1557 LIMIT 1

來源

2012-11-22 tomekfranek