When you use $sample on a view, MongoDB appends the stage to the end of the view's aggregation pipeline syntax. Therefore, the $sample stage on a view is never the first stage and always results in a collection scan.

$sample 根据集合的大小，N的大小以及 $sample 管道中的位置，使用两种方法之一来获取N个随机文档。 如果满足以下所有条件，请 $sample 使用伪随机游标选择文档：

Randomly selects the specified number of documents from the input documents. The $sample stage has the following syntax:

2018年4月28日 · 使用$ sample 可以从输入文档中 随机 选择指定数量的文档，可以用于采样或预览。

$sample 运算符是 MongoDB 中的一个聚合管道运算符，它的作用是随机抽取指定数量的文档作为输出结果。 该运算符可用于随机展示一些文档，或者用于测试目的。

Atlas provides sample data you can load into your Atlas clusters. You can use this data to quickly get started experimenting with data in MongoDB and using tools such as the Atlas Perform CRUD Operations in Atlas and MongoDB Charts.

2012年9月30日 · I have a mongo collection with documents. There is one field in every document which is 0 OR 1. I need to random sample 1000 records from the database and count the number of documents who have that field as 1. I need to do this sampling 1000 times. How do i do it ?

With an aggregation using { $sample: { size: 3 } }, I'll get 3 random documents returned. How can I use a percentage of all documents instead? Something that'd look like { $sample: { size: 50% } }?

目录概述使用$sample实现随机选取数据使用方法示例代码注意事项使用aggregate和$rand实现随机选取数据使用方法示例代码注意事项关于性能的考虑总结在MongoDB中,我 ...

MongoDB sample databases, some importing from popular datasources like SQL Server: Northwind - JavierCanon/mongodb-sample-database