MongoDB 如何实现子文档分组汇总

润乾软件

于 2021-08-11 18:03:09 发布

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分类专栏： JAVA计算文章标签： esProc SPL mongodb 数据分析 nosql

本文链接：https://blog.youkuaiyun.com/raqsoft/article/details/119613393

本文介绍如何在MongoDB中对嵌套子文档进行分组和汇总操作。通常，这种需求可以通过MapReduce实现，但过程复杂。而使用集算器SPL，可以更简便地完成这个任务，通过编写脚本对每条记录的子文档进行分组求和，并直接将结果赋值回子文档。

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MongoDB作为当前最流行的非关系型数据库，能通过嵌套子文档，实现一对多的关联关系。应用开发中，常会遇到对嵌套子文档结构的记录，进行分组汇总，如有数据：

{
"warehouseNsId":"10","brandId":37,"financeOwnerId":1231882808817905665,"amount":0,"items":[　{"goodsNsId":"1353","price":"256.00","count":3},　{"goodsNsId":"1799","price":"254.80","count":6},　{"goodsNsId":"1353","price":"256.00","count":10} ] },{ "warehouseNsId":"15","brandId":35,"financeOwnerId":1231882808817905600,"amount":0,"items":[　{"goodsNsId":"1327","price":"238.00","count":17},　{"goodsNsId":"1539","price":"154.80","count":25},　{"goodsNsId":"1327","price":"238.00","count":13},　{"goodsNsId":"1539","price":"154.80","count":15} ]}, ...

按每条记录的 items.goodsNsId 分组，对 items.count 求和，希望结果如下：

{
"warehouseNsId":"10","brandId":37,"financeOwnerId":1231882808817905665,"amount":0,"items":[　{"goodsNsId":"1353","price":"256.00","count":13},　{"goodsNsId":"1799","price":"254.80",