Slide 36
Slide 36 text
Stats With MapReduce
mapFunc = function() { emit(this.place, 1); }
reduceFunc = function(key, values) {
return Array.sum(values);
}
db.checkins.mapReduce(mapFunc,reduceFunc, { query: {
timestamp: {$gt:}}, out: result })
result = [{_id:”10gen HQ”, value: 17}, {…..}, {….}]
db.result.find({ value: {$gt: 15},
_id: {$in: [….., ….., …..]}
})