Mongodb Mongo映射减少错误_Mongodb_Mapreduce

Mongodb Mongo映射减少错误

mongodb mapreduce

Mongodb Mongo映射减少错误,mongodb,mapreduce,Mongodb,Mapreduce,作为MongoDB的新手，我正在尝试使用MapReduce。不幸的是，我得到了以下错误： mongos> db.events.mapReduce(m,r,"errors"); Fri Apr 12 11:39:15.637 JavaScript execution failed: map reduce failed:{ "ok" : 0, "errmsg" : "MR parallel processing failed: { errmsg: \"exception: r

作为MongoDB的新手，我正在尝试使用MapReduce。不幸的是，我得到了以下错误：

mongos> db.events.mapReduce(m,r,"errors");
Fri Apr 12 11:39:15.637 JavaScript execution failed: map reduce failed:{
    "ok" : 0,
    "errmsg" : "MR parallel processing failed: { errmsg: \"exception: reduce -> multiple not supported yet\", code: 10075, ok: 0.0 }"
} at src/mongo/shell/collection.js:L970
mongos>

我正在使用Mongo2.4.0

我的事件集合如下所示：

{ "sid" : "1UADM45MCGRTW ", "time" : ISODate("2013-04-08T11:33:13.229Z"), "class" : "S", "service" : "service1" }
{ "sid" : "1UADM45MCGRTW ", "time" : ISODate("2013-04-08T11:33:13.229Z"), "class" : "I", "service" : "service1" }
{ "sid" : "1UADM45MCGRTW ", "time" : ISODate("2013-04-08T11:33:13.236Z"), "class" : "E", "text" : "error message" }
{ "sid" : "1UADM45MCGRTW ", "time" : ISODate("2013-04-08T11:33:13.239Z"), "class" : "F", "service" : "service1" }

{ "sid" : "1UDO3H7YUOK08 ", "time" : ISODate("2013-04-08T11:33:08.095Z"), "class" : "S", "service" : "service2" }
{ "sid" : "1UDO3H7YUOK08 ", "time" : ISODate("2013-04-08T11:33:08.095Z"), "class" : "I", "service" : "service2" }
{ "sid" : "1UDO3H7YUOK08 ", "time" : ISODate("2013-04-08T11:33:08.173Z"), "class" : "E", "text" : "another error message" }
{ "sid" : "1UDO3H7YUOK08 ", "time" : ISODate("2013-04-08T11:33:08.188Z"), "class" : "F", "service" : "service2" }

{ "sid" : "1UDO3JVXIS2UZ ", "time" : ISODate("2013-04-08T11:28:39.480Z"), "class" : "I", "service" : "service1" }
{ ""sid" : "1UDO3JVXIS2UZ ", "time" : ISODate("2013-04-08T11:28:39.480Z"), "class" : "S", "service" : "service1" }
{ "sid" : "1UDO3JVXIS2UZ ", "time" : ISODate("2013-04-08T11:28:40.853Z"), "class" : "F", "service" : "service1" }
{ "sid" : "1UDO3JVXIS2UZ ", "time" : ISODate("2013-04-08T11:28:40.852Z"), "class" : "I", "service" : "service1" }

var m = function() {
    array = [];
    if (this.class == "E") {
        value = { time: this.time, error: this.text };
        array.push(value);
        emit(this.sid, {a:array});
    } else if (this.class == "F") {
        value = { service: this.service };
        array.push(value);
        emit(this.sid, {a:array});
    }
}


var r = function(key,values) {
    result = {a:[]};
    values.forEach(function (v) {
       result.a = v.a.concat(result.a);
    });
    return result;
}

db.events.mapReduce(m,r,"errors");

> db.errors.find().pretty()
{
    "_id" : "1UADM45MCGRTW ",
    "value" : {
        "a" : [
            {
                "service" : "service1"
            },
            {
                "time" : ISODate("2013-04-08T11:33:13.236Z"),
                "error" : "error message"
            }
        ]
    }
}
{
    "_id" : "1UDO3H7YUOK08 ",
    "value" : {
        "a" : [
            {
                "service" : "service2"
            },
            {
                "time" : ISODate("2013-04-08T11:33:08.173Z"),
                "error" : "another error message"
            }
        ]
    }
}
{
    "_id" : "1UDO3JVXIS2UZ ",
    "value" : {
        "a" : [
            {
                "service" : "service1"
            }
        ]
    }
}

我的意图是获取所有“E”条目，并将它们与“F”条目的对应“sid”的“service”字段相结合。所以这应该是非常简单的，但我无法让它运行（因为上面的错误）

我使用的map/reduce函数有：

var m = function() {
    if (this.class == "E") {
        value = { time: this.time, error: this.text };
        emit(this.sid, value);
    } else if (this.class == "F") {
        value = { service: this.service };
        emit(this.sid, value);
    }
}


var r = function(key,values) {
    return values;
}

db.events.mapReduce(m,r,"errors");

根据文件（） “reduce函数必须返回一个对象，该对象的类型必须与map函数发出的值的类型相同”

当您发射一个对象时，reduce也应该发射一个对象-因此将

值

包装到一个对象中，您就可以开始了。

根据文档（） “reduce函数必须返回一个对象，该对象的类型必须与map函数发出的值的类型相同”

当你发射一个对象时，reduce也应该发射一个对象-因此在一个对象中包装

值

，你就可以开始了。

问题是你想为每个键积累所有错误，这意味着你必须发射一个文档数组，然后reduce必须将它们组合成一个数组（因为它将接收一组数组）

另一个问题是，您希望将每个唯一cid的不同类组合成一些组合的简化结果，但reduce函数甚至没有尝试这样做

很难知道每个sid可能会得到多少不同的类值，但如果它与您提供的示例数据类似，我猜您希望得到如下结果：

{ "sid" : "1UADM45MCGRTW ", "time" : ISODate("2013-04-08T11:33:13.229Z"), "class" : "S", "service" : "service1" }
{ "sid" : "1UADM45MCGRTW ", "time" : ISODate("2013-04-08T11:33:13.229Z"), "class" : "I", "service" : "service1" }
{ "sid" : "1UADM45MCGRTW ", "time" : ISODate("2013-04-08T11:33:13.236Z"), "class" : "E", "text" : "error message" }
{ "sid" : "1UADM45MCGRTW ", "time" : ISODate("2013-04-08T11:33:13.239Z"), "class" : "F", "service" : "service1" }

{ "sid" : "1UDO3H7YUOK08 ", "time" : ISODate("2013-04-08T11:33:08.095Z"), "class" : "S", "service" : "service2" }
{ "sid" : "1UDO3H7YUOK08 ", "time" : ISODate("2013-04-08T11:33:08.095Z"), "class" : "I", "service" : "service2" }
{ "sid" : "1UDO3H7YUOK08 ", "time" : ISODate("2013-04-08T11:33:08.173Z"), "class" : "E", "text" : "another error message" }
{ "sid" : "1UDO3H7YUOK08 ", "time" : ISODate("2013-04-08T11:33:08.188Z"), "class" : "F", "service" : "service2" }

{ "sid" : "1UDO3JVXIS2UZ ", "time" : ISODate("2013-04-08T11:28:39.480Z"), "class" : "I", "service" : "service1" }
{ ""sid" : "1UDO3JVXIS2UZ ", "time" : ISODate("2013-04-08T11:28:39.480Z"), "class" : "S", "service" : "service1" }
{ "sid" : "1UDO3JVXIS2UZ ", "time" : ISODate("2013-04-08T11:28:40.853Z"), "class" : "F", "service" : "service1" }
{ "sid" : "1UDO3JVXIS2UZ ", "time" : ISODate("2013-04-08T11:28:40.852Z"), "class" : "I", "service" : "service1" }

var m = function() {
    array = [];
    if (this.class == "E") {
        value = { time: this.time, error: this.text };
        array.push(value);
        emit(this.sid, {a:array});
    } else if (this.class == "F") {
        value = { service: this.service };
        array.push(value);
        emit(this.sid, {a:array});
    }
}


var r = function(key,values) {
    result = {a:[]};
    values.forEach(function (v) {
       result.a = v.a.concat(result.a);
    });
    return result;
}

db.events.mapReduce(m,r,"errors");

> db.errors.find().pretty()
{
    "_id" : "1UADM45MCGRTW ",
    "value" : {
        "a" : [
            {
                "service" : "service1"
            },
            {
                "time" : ISODate("2013-04-08T11:33:13.236Z"),
                "error" : "error message"
            }
        ]
    }
}
{
    "_id" : "1UDO3H7YUOK08 ",
    "value" : {
        "a" : [
            {
                "service" : "service2"
            },
            {
                "time" : ISODate("2013-04-08T11:33:08.173Z"),
                "error" : "another error message"
            }
        ]
    }
}
{
    "_id" : "1UDO3JVXIS2UZ ",
    "value" : {
        "a" : [
            {
                "service" : "service1"
            }
        ]
    }
}

在您的示例中，生成的集合如下所示：

{ "sid" : "1UADM45MCGRTW ", "time" : ISODate("2013-04-08T11:33:13.229Z"), "class" : "S", "service" : "service1" }
{ "sid" : "1UADM45MCGRTW ", "time" : ISODate("2013-04-08T11:33:13.229Z"), "class" : "I", "service" : "service1" }
{ "sid" : "1UADM45MCGRTW ", "time" : ISODate("2013-04-08T11:33:13.236Z"), "class" : "E", "text" : "error message" }
{ "sid" : "1UADM45MCGRTW ", "time" : ISODate("2013-04-08T11:33:13.239Z"), "class" : "F", "service" : "service1" }

{ "sid" : "1UDO3H7YUOK08 ", "time" : ISODate("2013-04-08T11:33:08.095Z"), "class" : "S", "service" : "service2" }
{ "sid" : "1UDO3H7YUOK08 ", "time" : ISODate("2013-04-08T11:33:08.095Z"), "class" : "I", "service" : "service2" }
{ "sid" : "1UDO3H7YUOK08 ", "time" : ISODate("2013-04-08T11:33:08.173Z"), "class" : "E", "text" : "another error message" }
{ "sid" : "1UDO3H7YUOK08 ", "time" : ISODate("2013-04-08T11:33:08.188Z"), "class" : "F", "service" : "service2" }

{ "sid" : "1UDO3JVXIS2UZ ", "time" : ISODate("2013-04-08T11:28:39.480Z"), "class" : "I", "service" : "service1" }
{ ""sid" : "1UDO3JVXIS2UZ ", "time" : ISODate("2013-04-08T11:28:39.480Z"), "class" : "S", "service" : "service1" }
{ "sid" : "1UDO3JVXIS2UZ ", "time" : ISODate("2013-04-08T11:28:40.853Z"), "class" : "F", "service" : "service1" }
{ "sid" : "1UDO3JVXIS2UZ ", "time" : ISODate("2013-04-08T11:28:40.852Z"), "class" : "I", "service" : "service1" }

var m = function() {
    array = [];
    if (this.class == "E") {
        value = { time: this.time, error: this.text };
        array.push(value);
        emit(this.sid, {a:array});
    } else if (this.class == "F") {
        value = { service: this.service };
        array.push(value);
        emit(this.sid, {a:array});
    }
}


var r = function(key,values) {
    result = {a:[]};
    values.forEach(function (v) {
       result.a = v.a.concat(result.a);
    });
    return result;
}

db.events.mapReduce(m,r,"errors");

> db.errors.find().pretty()
{
    "_id" : "1UADM45MCGRTW ",
    "value" : {
        "a" : [
            {
                "service" : "service1"
            },
            {
                "time" : ISODate("2013-04-08T11:33:13.236Z"),
                "error" : "error message"
            }
        ]
    }
}
{
    "_id" : "1UDO3H7YUOK08 ",
    "value" : {
        "a" : [
            {
                "service" : "service2"
            },
            {
                "time" : ISODate("2013-04-08T11:33:08.173Z"),
                "error" : "another error message"
            }
        ]
    }
}
{
    "_id" : "1UDO3JVXIS2UZ ",
    "value" : {
        "a" : [
            {
                "service" : "service1"
            }
        ]
    }
}

您可能可以添加一个finalize函数，将此数组转换为单个文档的结果，但这取决于您想要的结果集合的格式以及每个sid的预期输入。

问题在于，您想要累积每个键的所有错误，这意味着您必须发出一个文档，然后reduce必须将它们合并到一个数组中（因为它将接收一个数组数组）

另一个问题是，您希望将每个唯一cid的不同类组合成一些组合的简化结果，但reduce函数甚至没有尝试这样做

很难知道每个sid可能会得到多少不同的类值，但如果它与您提供的示例数据类似，我猜您希望得到如下结果：

{ "sid" : "1UADM45MCGRTW ", "time" : ISODate("2013-04-08T11:33:13.229Z"), "class" : "S", "service" : "service1" }
{ "sid" : "1UADM45MCGRTW ", "time" : ISODate("2013-04-08T11:33:13.229Z"), "class" : "I", "service" : "service1" }
{ "sid" : "1UADM45MCGRTW ", "time" : ISODate("2013-04-08T11:33:13.236Z"), "class" : "E", "text" : "error message" }
{ "sid" : "1UADM45MCGRTW ", "time" : ISODate("2013-04-08T11:33:13.239Z"), "class" : "F", "service" : "service1" }

{ "sid" : "1UDO3H7YUOK08 ", "time" : ISODate("2013-04-08T11:33:08.095Z"), "class" : "S", "service" : "service2" }
{ "sid" : "1UDO3H7YUOK08 ", "time" : ISODate("2013-04-08T11:33:08.095Z"), "class" : "I", "service" : "service2" }
{ "sid" : "1UDO3H7YUOK08 ", "time" : ISODate("2013-04-08T11:33:08.173Z"), "class" : "E", "text" : "another error message" }
{ "sid" : "1UDO3H7YUOK08 ", "time" : ISODate("2013-04-08T11:33:08.188Z"), "class" : "F", "service" : "service2" }

{ "sid" : "1UDO3JVXIS2UZ ", "time" : ISODate("2013-04-08T11:28:39.480Z"), "class" : "I", "service" : "service1" }
{ ""sid" : "1UDO3JVXIS2UZ ", "time" : ISODate("2013-04-08T11:28:39.480Z"), "class" : "S", "service" : "service1" }
{ "sid" : "1UDO3JVXIS2UZ ", "time" : ISODate("2013-04-08T11:28:40.853Z"), "class" : "F", "service" : "service1" }
{ "sid" : "1UDO3JVXIS2UZ ", "time" : ISODate("2013-04-08T11:28:40.852Z"), "class" : "I", "service" : "service1" }

var m = function() {
    array = [];
    if (this.class == "E") {
        value = { time: this.time, error: this.text };
        array.push(value);
        emit(this.sid, {a:array});
    } else if (this.class == "F") {
        value = { service: this.service };
        array.push(value);
        emit(this.sid, {a:array});
    }
}


var r = function(key,values) {
    result = {a:[]};
    values.forEach(function (v) {
       result.a = v.a.concat(result.a);
    });
    return result;
}

db.events.mapReduce(m,r,"errors");

> db.errors.find().pretty()
{
    "_id" : "1UADM45MCGRTW ",
    "value" : {
        "a" : [
            {
                "service" : "service1"
            },
            {
                "time" : ISODate("2013-04-08T11:33:13.236Z"),
                "error" : "error message"
            }
        ]
    }
}
{
    "_id" : "1UDO3H7YUOK08 ",
    "value" : {
        "a" : [
            {
                "service" : "service2"
            },
            {
                "time" : ISODate("2013-04-08T11:33:08.173Z"),
                "error" : "another error message"
            }
        ]
    }
}
{
    "_id" : "1UDO3JVXIS2UZ ",
    "value" : {
        "a" : [
            {
                "service" : "service1"
            }
        ]
    }
}

在您的示例中，生成的集合如下所示：

{ "sid" : "1UADM45MCGRTW ", "time" : ISODate("2013-04-08T11:33:13.229Z"), "class" : "S", "service" : "service1" }
{ "sid" : "1UADM45MCGRTW ", "time" : ISODate("2013-04-08T11:33:13.229Z"), "class" : "I", "service" : "service1" }
{ "sid" : "1UADM45MCGRTW ", "time" : ISODate("2013-04-08T11:33:13.236Z"), "class" : "E", "text" : "error message" }
{ "sid" : "1UADM45MCGRTW ", "time" : ISODate("2013-04-08T11:33:13.239Z"), "class" : "F", "service" : "service1" }

{ "sid" : "1UDO3H7YUOK08 ", "time" : ISODate("2013-04-08T11:33:08.095Z"), "class" : "S", "service" : "service2" }
{ "sid" : "1UDO3H7YUOK08 ", "time" : ISODate("2013-04-08T11:33:08.095Z"), "class" : "I", "service" : "service2" }
{ "sid" : "1UDO3H7YUOK08 ", "time" : ISODate("2013-04-08T11:33:08.173Z"), "class" : "E", "text" : "another error message" }
{ "sid" : "1UDO3H7YUOK08 ", "time" : ISODate("2013-04-08T11:33:08.188Z"), "class" : "F", "service" : "service2" }

{ "sid" : "1UDO3JVXIS2UZ ", "time" : ISODate("2013-04-08T11:28:39.480Z"), "class" : "I", "service" : "service1" }
{ ""sid" : "1UDO3JVXIS2UZ ", "time" : ISODate("2013-04-08T11:28:39.480Z"), "class" : "S", "service" : "service1" }
{ "sid" : "1UDO3JVXIS2UZ ", "time" : ISODate("2013-04-08T11:28:40.853Z"), "class" : "F", "service" : "service1" }
{ "sid" : "1UDO3JVXIS2UZ ", "time" : ISODate("2013-04-08T11:28:40.852Z"), "class" : "I", "service" : "service1" }

var m = function() {
    array = [];
    if (this.class == "E") {
        value = { time: this.time, error: this.text };
        array.push(value);
        emit(this.sid, {a:array});
    } else if (this.class == "F") {
        value = { service: this.service };
        array.push(value);
        emit(this.sid, {a:array});
    }
}


var r = function(key,values) {
    result = {a:[]};
    values.forEach(function (v) {
       result.a = v.a.concat(result.a);
    });
    return result;
}

db.events.mapReduce(m,r,"errors");

> db.errors.find().pretty()
{
    "_id" : "1UADM45MCGRTW ",
    "value" : {
        "a" : [
            {
                "service" : "service1"
            },
            {
                "time" : ISODate("2013-04-08T11:33:13.236Z"),
                "error" : "error message"
            }
        ]
    }
}
{
    "_id" : "1UDO3H7YUOK08 ",
    "value" : {
        "a" : [
            {
                "service" : "service2"
            },
            {
                "time" : ISODate("2013-04-08T11:33:08.173Z"),
                "error" : "another error message"
            }
        ]
    }
}
{
    "_id" : "1UDO3JVXIS2UZ ",
    "value" : {
        "a" : [
            {
                "service" : "service1"
            }
        ]
    }
}

您可能可以添加finalize函数将此数组转换为单个文档的结果，但这取决于您想要的结果集合的格式以及每个sid的预期输入