mongodb缺少数据

Question

以下是我的Map、Reduce和finalize函数。有4条记录与键匹配，当用较少的数据调用mapreduce（100秒）时，结果正确，但当用较多的数据调用mapreduce时（只有1000秒），结果始终为2。我检查了Reduce函数，在我看来它是正确的，即使它在内部被多次调用以获取更大的数据。这越来越奇怪了，我花了很长时间，仍然没能把它做好。

var map1 = function(){
    var mapPosCnt = 0, mapPosSum = 0, mapZeroCnt = 0;
    if (isNumber(this.val1)){
        if(this.val1.toPrecision(10)  > 0.0000000000){
            mapPosCnt = 1;
            mapPosSum = this.val1;
        }else{
            mapZeroCnt = 1;
        }
    }else{
        mapPosCnt = 0, mapPosSum = 0, mapZeroCnt = 0;
    }
    emit({key1: this.key1, key2: this.key2+'', val1: 'val1'}
        ,{key1: this.key1, key2: this.key2+'', posCnt: mapPosCnt, posSum: mapPosSum, posAvg: 0, zeroCnt: mapZeroCnt, val1: this.val1});
}
var reduce1 = function(key, values){
    var retval = {key1: key.CE, key2: key.key2, posCnt: 0, posSum: 0, posAvg: 0, zeroCnt: 0, val1: 0};
    values.forEach(function(value){
        if (isNumber(value.val1)){
            if(value.val1.toPrecision(10)  > 0.0000000000){
                retval.posCnt += 1;
                retval.posSum += value.val1;
            }else{
                retval.zeroCnt += 1;
            }
        }
    })
    return retval;
}
var finalize1 = function(key, value){
    value.key2 = value.key2.toString();
    if(value.posCnt > 0){
        value.posSum = Math.round(value.posSum * Math.pow(10, 6)) / Math.pow(10, 6);
        value.posAvg = Math.round((value.posSum/value.posCnt) * Math.pow(10, 6)) / Math.pow(10, 6);
    }
    return value;
}
collection1.mapReduce(map1, reduce1, {out: {merge: 'collection2'}, finalize: finalize1}, function(err, collection){});

Answer 1

如果没有文档来测试它，我猜有点，但我可以看到几个问题：

1. 发射/减少的值不应包括关键字段。因此，您的发射值应该是这样的：{ posCnt: mapPosCnt, posSum: mapPosSum, zeroCnt: mapZeroCnt }
2. reduce函数不应该像您所做的那样尝试重新应用发射逻辑，而是应该通过对值求和来聚合具有相同键的值

所以reduce1应该看起来像：

var reduce1 = function(key, values){
    var retval = { posCnt: 0, posSum: 0, zeroCnt: 0 };
    values.forEach(function(value){
        retval.posCnt += value.posCnt;
        retval.posSum += value.posSum;
        retval.zeroCnt += value.zeroCnt;
    });
    return retval;
};