您正在预加载吨，这将为您提供大量数据，您可以在代码中过滤我们的数据，但是如果您使用 join / 5 ：

You're preloading a ton, which will get you lots of data you could filter our in code, but the database can return much less data if you use join/5:

假设我已经解释了您的方案正确，这就是我的工作。

Assuming I've interpreted your scheme correctly, here's what I'd do.

import Ecto.Query

query =
  from s in MyApp.Snapmail,
  join: sc in assoc(s, :snapmail_cameras),
  join: c in assoc(sc, :camera),
  where: c.status != ^"status_finished"

MyApp.Repo.all(query)

这只会返回 Snapmails 而没有所有这些预加载，但是您始终可以添加`preload / 3'在查询结束时将数据导入。

This will only return Snapmails without all those preloads, but you can always add a `preload/3' at the end of your query to bring that data in.