预加载数据以加快视图加载时间 - rails

Question

我正在研究 rails 加快加载时间的技术。我现在正在处理一个在渲染时渲染大量数据的页面。我正在尝试逐步完成每个负载，看看是否可以优化时间。

我目前遇到的问题是这个；

 (5.4ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23022]]
   (4.4ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23023]]
   (4.2ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23024]]
   (6.0ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23029]]
   (7.1ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23121]]
   (6.0ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23180]]
   (4.2ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23229]]
   (4.2ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23250]]
   (6.6ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23254]]
   (4.4ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23255]]
   (4.0ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23259]]
   (6.5ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23154]]
   (6.6ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23177]]
   (5.1ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23201]]
   (4.2ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23221]]
   (4.1ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23232]]
   (7.9ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23235]]
   (4.3ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23237]]
   (4.1ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23238]]
   (5.9ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23248]]
   (7.8ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23295]]
   (6.8ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23119]]
   (4.2ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23123]]
   (4.1ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23178]]
   (7.9ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23231]]
   (4.4ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23239]]
   (4.3ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23240]]
   (6.4ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23241]]
   (5.1ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23243]]
   (6.7ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23245]]
   (4.3ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23247]]
   (4.2ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23249]]
   (6.9ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23251]]
   (4.4ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23256]]
   (4.2ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23257]]
   (6.5ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23275]]
   (6.4ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23350]]
   (5.0ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23272]]
   (4.2ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23296]]
   (4.0ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23401]]
   (8.8ms)  SELECT COUNT(*) FROM "attendees" WHERE "attendees"."rsvp_id" =   [["rsvp_id", 23347]]

我是从这段代码中得到的：

def number_attending
  rsvp.attendees.count
end

所以RSVPS有很多参加者。我在这里调用那个方法。

<% rsvps.each do |rsvp| %>
 <span class="event-response__indicator event-response__indicator--guests" title="<%= rsvp.number_attending %> Guests">
<% end %>

所以问题来了。我不想在页面加载时遍历每个 rsvp 和与会者。有没有办法预加载该数据。像 Eagerloading 这样的东西？如果是这样，我如何根据给定的信息实施它？

Answer 1

好吧，你没有说明你是如何查询 rsvps 的，所以我会认为它是 rsvps = Rsvp.all。你可以只添加一个 includes 方法，所以它会像这样 rsvps = Rsvp.includes(:attendees).all.

另外我不确定它是否会在运行这一行 rsvp.attendees.count 时避免查询。我运行遇到 count 方法触发查询但 size 方法没有触发查询的情况，因此您可能必须将此行替换为 rsvp.attendees.size.

Answer 2

查看 this link，这专门用于避免 n+1 次查询计数。

这解释了如何执行连接查询或为其创建视图

预加载数据以加快视图加载时间 - rails

Preloading data to speed up view load time - rails

ruby-on-rails

eager-loading