$ orderby和Sort之间的MongoDB区别 [英] MongoDB difference between $orderby and Sort

问题描述

我想获取最新的文档，该文档显然是单个文档，因此findOne应该可以正常工作.但是findOne此处返回插入的第一个文档.因此，我现在有两个选择，或者将$orderBy与findOne一起使用，或者将.sort()函数与.limit()在find()

I want to fetch the latest document, which obviously is a single document, thus findOne should work fine. But findOne here returns the first document inserted. So I have two options now either use $orderBy with findOne or use .sort() function with .limit() in find()

使用$ orderBy，它看起来像:

Using $orderBy it would look something like:

db.collection.findOne({$query:{},$orderby:{_id:-1}}) 

并使用排序:

db.collection.find().sort({_id:-1}).limit(1).pretty()

两者都能正常工作，我只是想知道我在这里更喜欢哪个查询?在性能方面，或者两者在内部的工作方式相同，两者之间没有这种差异.

Both work fine, I just wanted to know which query should I prefer here? In terms of performance, or does both of them work the same way internally and there is no such difference between the two.

推荐答案

从Mongo 3.2开始，$orderby为

As of Mongo 3.2, $orderby is deprecated.

文档明确说出:

不建议使用$ orderby运算符.改用cursor.sort().

The $orderby operator is deprecated. Use cursor.sort() instead.

不幸的是，findOne()不支持sort()方法，因此您需要切换到find():

Unfortunately, findOne() doesn't support the sort() method, so you'll need to switch to find():

db.collection.find({}).sort({'key': -1}).limit(1)

这将返回cursor，因此您需要从游标中提取第一个结果.

This will return a cursor, so you'll then need to pull the first result from the cursor.

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