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MongoDB映射-还原结果不准确_Mongodb_Mapreduce - Fatal编程技术网

MongoDB映射-还原结果不准确

MongoDB映射-还原结果不准确,mongodb,mapreduce,Mongodb,Mapreduce,我在MongoDB中有如下数据结构 { "_id" : ObjectId("523aab00045624a385e5f549"), "name" : "English Book 29", "SKU" : 1000549081, "price" : 249000, "image" : null, "category_id" : ObjectId("523a7802b50418baf38b4575"), "category_name" : "E

我在MongoDB中有如下数据结构

{
    "_id" : ObjectId("523aab00045624a385e5f549"),
    "name" : "English Book 29",
    "SKU" : 1000549081,
    "price" : 249000,
    "image" : null,
    "category_id" : ObjectId("523a7802b50418baf38b4575"),
    "category_name" : "English Book",
    "details" : {
        "Title" : "Title 549081",
        "Binding" : 1,
        "Author" : "Author 0",
        "Publication data" : 0.5263832447608386,
        "Publisher name" : "Publisher name 14",
        "Number of page" : 90
    }
}
书籍装订有两个价值: 0表示软绑定,1表示硬绑定。我将Map Reduce写入每个值的统计信息

var map = function()
{
  for(var key in this.details)
  {
    if(key == 'Binding')
    { 
        emit({name: key}, {
          'data':
          [
            {
              name: this.details[key],
              count: 1
            }
          ]
        });      
    }
  }
};

var reduce = function (key, values) {
  var reduced = {};
  for(var i in values)
  {
    var inter = values[i];
    for(var j in inter.data)
    {
      if(typeof(reduced[inter.data[j].name]) != "undefined")
      {
        reduced[inter.data[j].name] += inter.data[j].count;
      }
      else
      {
        reduced[inter.data[j].name] = 1;
      }
    }
  }
  return reduced;
};
当我使用小数据(50条记录)运行时,结果会准确返回。但当我使用真实数据(192000条记录)运行它时,结果返回的并不准确。结果如下

{
    "_id" : {
        "name" : "Binding"
    },
    "value" : {
        "0" : 50,
        "1" : 50
    }
}
"counts" : {
        "input" : 192000,
        "emit" : 192000,
        "reduce" : 1920,
        "output" : 1
    },
当映射/减少完成时,我检查了返回数据,结果如下

{
    "_id" : {
        "name" : "Binding"
    },
    "value" : {
        "0" : 50,
        "1" : 50
    }
}
"counts" : {
        "input" : 192000,
        "emit" : 192000,
        "reduce" : 1920,
        "output" : 1
    },
有什么问题吗。欢迎任何建议、解释。
感谢并致以最诚挚的问候,

在昨天研究了Map/Reduce之后,我意识到,“Emit”一次发送100个元素,“Reduce”在这个数据集上执行。所以我上面的代码是错误的,因为它只对小数据集进行“求和”。 下面是我的MapReduce新代码

var map = function ()
{
    for(var key in this.details)
    {
        if(key == 'Binding')
        {
            var value = {};
            value[this.details[key]] = 1;
            emit(key, value);
        }
    }
}

var reduce = function (key, values)
{
    var reduced = {};
    for(var idx = 0; idx < values.length; idx++)
    {
        var inner = values[idx];
        for (var j in inner)
        {
            if (typeof (reduced[j]) == 'undefined')
            {
                reduced[j] = 0;
            }
            reduced[j] += inner[j];
        }
    }
    return reduced;
}
var map=函数()
{
for(此.details中的var键)
{
如果(键==“绑定”)
{
var值={};
值[this.details[key]]=1;
发射(键、值);
}
}
}
var reduce=函数(键、值)
{
var-reduced={};
对于(var idx=0;idx
我在这里为任何遇到类似情况的人发帖。谢谢你的阅读