Active Record或mysql中的批次计数

My goal is to export votes, per model object for a given collection. In this example I use .all, but in the wild, it will be a .where that yields the large set. I have the following query that I am concerned about:

我的目标是根据给定集合的每个模型对象导出投票。在这个例子中,我使用.all,但在野外,它将是一个产生大集合的.where。我有以下关注的问题:

Model.all.each{|x|puts x.votes.count}.explain

   (0.4ms)  SELECT COUNT(*) FROM `votes` WHERE `votes`.`entry_id` = 1
0
   (0.3ms)  SELECT COUNT(*) FROM `votes` WHERE `votes`.`entry_id` = 2
0
   (0.4ms)  SELECT COUNT(*) FROM `votes` WHERE `votes`.`entry_id` = 3
1
   (0.3ms)  SELECT COUNT(*) FROM `votes` WHERE `votes`.`entry_id` = 4
0
   (0.2ms)  SELECT COUNT(*) FROM `votes` WHERE `votes`.`entry_id` = 5
0

Individually count is very quick, but I don't feel comfortable calling All, especially when I have a collection in the thousands or millions. Is there a way to count records as a batch opporation?

单独计数非常快,但我觉得打电话给All感觉不舒服,特别是当我有数千或数百万的收藏品时。有没有办法将记录计为批量操作?

1 个解决方案

#1

Not sure what you mean by "All", but do the same thing, only try using GROUP BY the ID and the COUNT function. Something like this:

不确定你的意思是“全部”,但做同样的事情,只尝试使用GROUP BY ID和COUNT函数。像这样的东西:

SELECT COUNT(*) FROM Votes GROUP BY entry_id

1 个解决方案

#1

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