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23decxf 发表于 2016-12-2 08:17:41

mongo加sum方法

http://stackoverflow.com/questions/4621300/how-i-can-sum-all-the-values-of-a-key-in-a-collection-in-mongodb
http://www.letrails.cn/archives/add-sum-method-for-mongo-mapper/
db.testmap.save({"id":1,"max":2.2,})
map = function() { emit("sum", this.max); }
red = function(k, v) { var i, sum = 0;for (i in v) {sum += v;}return sum;}
res = db.testmap.mapReduce(map, red);
db.find()

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