mysql - 如何减少ActiveRecord总时间

我正在优化我的查询，但我不知道如何减少总的ActiveRecord时间。
我有两个简单的查询在1.0ms和0.6ms中运行，但是ActiveRecord时间是14.3ms的10倍，比我的查询的总和还要高。如果我再添加其他查询，ActiveRecord的时间将呈指数增长。
我知道ActiveRecord做了一些black magic behind the scene 的事情，所以我想知道怎样才能减少实现它所花费的时间。
查询

Binda::Structure.where(slug: 'page').first.components.order('position')

原木

Processing by PagesController#index as HTML
  Binda::Structure Load (1.0ms)  SELECT  "binda_structures".* FROM "binda_structures" WHERE "binda_structures"."slug" = $1 ORDER BY "binda_structures"."id" ASC LIMIT $2  [["slug", "page"], ["LIMIT", 1]]
  Rendering pages/index.html.erb within layouts/application
  Binda::Component Load (0.6ms)  SELECT "binda_components".* FROM "binda_components" WHERE "binda_components"."structure_id" = $1 ORDER BY position  [["structure_id", 2]]
  Rendered pages/index.html.erb within layouts/application (15.3ms)
Completed 200 OK in 118ms (Views: 42.5ms | ActiveRecord: 14.3ms)

更新#1
将查询改为following将AR时间从14.3ms加快到7.1ms，并将总时间从118ms降低到39ms。太好了！

id = Binda::Structure.where( slug: 'page' ).pluck(:id)
Binda::Component.where( structure_id: id ).order( 'position' )

Processing by PagesController#index as HTML
   (0.5ms)  SELECT "binda_structures"."id" FROM "binda_structures" WHERE "binda_structures"."slug" = $1  [["slug", "page"]]
  Rendering pages/index.html.erb within layouts/application
  Binda::Component Load (1.2ms)  SELECT "binda_components".* FROM "binda_components" WHERE "binda_components"."structure_id" = 2 ORDER BY position
  Rendered pages/index.html.erb within layouts/application (20.4ms)
Completed 200 OK in 39ms (Views: 29.4ms | ActiveRecord: 7.1ms)

更新#2
正如Max在注释中提到的，还可以将请求减少到单个查询。与前一种解决方案的差别不大（32msfrom39ms）。

Binda::Component.where( structure_id: Binda::Structure.where( slug: 'page' ) ).order( 'position' )

Processing by PagesController#index as HTML
  Rendering pages/index.html.erb within layouts/application
  Binda::Component Load (0.8ms)  SELECT "binda_components".* FROM "binda_components" WHERE "binda_components"."structure_id" IN (SELECT "binda_structures"."id" FROM "binda_structures" WHERE "binda_structures"."slug" = $1) ORDER BY position  [["slug", "page"]]
  Rendered pages/index.html.erb within layouts/application (3.6ms)
Completed 200 OK in 32ms (Views: 27.8ms | ActiveRecord: 0.8ms)

最佳答案

现在还不清楚到底是什么在消耗这么多时间。42.5ms和14.3ms加起来不等于118ms。
你需要在你的代码中找到瓶颈。尝试在活动记录语句之后调用to_sql方法。然后直接对数据库执行该查询。
排除不同的事情。可能尝试初始化此模型的单个实例，以查看速度是否较慢。您是否正在运行任何复杂的初始化例程或AR回调？模型中是否有外呼？

关于mysql - 如何减少ActiveRecord总时间，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/45845235/