adding integer value.
input data
db.test2.save({"keyword":"다음", "freq":10000})
db.test2.save({"keyword":"네이버", "freq":20000})
db.test2.save({"keyword":"다음", "freq":55555})
map function
m = function(){ emit(this.keyword, { freq_sum:this.freq}); }
reduce function
r = function(key, values){
var total=0
values.forEach(function(x){
total += x.freq_sum
})
return {"freq_sum": total };
}
call map/reduce
db.test2.mapReduce(m,r, {out:"mr_result"})
out data
db.mr_result.find()
{ "_id" : "네이버", "value" : { "freq_sum" : 20000 } }
{ "_id" : "다음", "value" : { "freq_sum" : 65555 } }
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