云数据库 MongoDB 版mapreduce案例分析-阿里云

MongoDB mapReduce案例分析二

例2、查找订单中一个商品对应的订单总数和这个商品每个订单的平均销售数量 1、先看订单表orders的数据结构如下图这样的数据共有6条，如下，只列出了items这个字段 2、下面给出map函数 ...

MongoDB mapReduce案例分析一

例子1：找出集合中的所有键以及每个键对应的次数 MongoDB没有模式，所以并不知道每个文档有多少个键。通常找到集合中的所有键的最好方法就是利用MapReduce。好了，接下来看例子吧。 1、首先通过mo...

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更新时间 2022-11-15 14:50:02

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