Rails太多查询？

Question

Rails太多查询？

只是做一些Rails并注意到当使用@products.each do它在单个页面上显示30个产品时,好像在后台有很多查询,请参阅下面的我的控制台输出.这是对的,还是我读错了？

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

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更新:对不起,我是专门谈论CACHE线路,这些是否意味着每次都不运行这些查询？

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

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以下是产品部分的代码:

<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 />

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Answer 1

Jim*_*mmy 5

您可能希望急于加载您的产品/商家/等

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

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(我不知道你的关系,所以根据需要使用)

关于你的缓存问题进行编辑,没有那些查询不是针对服务器运行的,但你一定要考虑急切加载,这样你就不会进行不必要的查询了

有关详细信息,请参阅以下内容

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

http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html < - 请参阅Eager loading

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