Rails слишком много запросов?

Question

Просто выполнил несколько Rails и заметил, что при отображении 30 продуктов на одной странице с использованием @products.each do это выглядит так, как будто в фоновом режиме выполняется много запросов, см. Ниже мой вывод на консоль.Это правильно, или я читаю это совершенно неправильно?

Category Load (0.1ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."name" = 'bras') LIMIT 1
  Product Load (28.0ms)  SELECT "products".* FROM "products" WHERE ("products".category_id = 48)
  Brand Load (0.2ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  Category Load (0.1ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  Merchant Load (0.1ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (16.9ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.8ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.5ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.5ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.5ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.5ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.5ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.5ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.7ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.4ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.5ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.4ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.5ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.5ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.6ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.5ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.5ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.5ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.5ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.6ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.4ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.5ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.5ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (2.0ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.4ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.5ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.5ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.6ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1
Rendered products/_product.html.erb (1.5ms)
  CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
  CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
  CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1

Обновление: Извините, я специально говорю о строках CACHE, это означает, что эти запросы не запускаются каждый раз?

CACHE (0.0ms)  SELECT "brands".* FROM "brands" WHERE ("brands"."id" = 408) LIMIT 1
CACHE (0.0ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" = 48) LIMIT 1
CACHE (0.0ms)  SELECT "merchants".* FROM "merchants" WHERE ("merchants"."id" = 2) LIMIT 1

Вот код из частичного продукта:

<h3><%= product.product_name %></h3>

<img src="<%= product.image %>" align="right" alt="<%= product.product_name %>" height="200" />

<p><%= truncate(product.product_description, :length => 300, :omission => "...") %></p>

<p><%= product.price %></p>

<p>Brand: <%= product.brand.brand_name %></p>

<p>Category: <%= product.category.category_name %></p>

<p>Merchant: <%= product.merchant.merchant_name %></p>

<p><a href="<%= product.link %>" target="_blank">More information</a></p>

<hr />

Answer 1

Возможно, вы захотите загрузить ваши продукты / продавцов / и т. Д.

@product = Product.find(conditions, :include => {:category, :brand, :merchant})

(я не знаю ваших отношений, поэтому используйте по мере необходимости)

РЕДАКТИРОВАТЬ в отношении вашего вопроса кешаНет, эти запросы не выполняются на сервере, но вы обязательно должны внимательно следить за загрузкой, чтобы избежать ненужных запросов

Подробнее см.

http://rails -bestpractices.com / posts / 29-fix-n-1-query

http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html <- см. Eager loading </p>

Answer 2

Эти запросы CACHEd запускаются только один раз, но вы все равно хотите присоединиться к ним изначально. В вашем контроллере вы захотите сделать @products = Product.all(:include => [:brand, :category, :merchant])

Кроме того, немного дороже многократно рендерить небольшой фрагмент. Мне повезло, что они сами зациклились на коллекции:

Продукты / _products.html.erb

<% products.each do |product| %>
<h3><%= product.product_name %></h3>

<img src="<%= product.image %>" align="right" alt="<%= product.product_name %>" height="200" />

<p><%= truncate(product.product_description, :length => 300, :omission => "...") %></p>

<p><%= product.price %></p>

<p>Brand: <%= product.brand.brand_name %></p>

<p>Category: <%= product.category.category_name %></p>

<p>Merchant: <%= product.merchant.merchant_name %></p>

<p><a href="<%= product.link %>" target="_blank">More information</a></p>

<hr />
<% end %>