将行旋转到MongoDB中的列 [英] Pivot rows to columns in MongoDB

问题描述

相关问题是在sql中有效地将行转换为列服务器.但是答案是特定于SQL的.

The relevant question is Efficiently convert rows to columns in sql server. But the answer is specific to SQL.

我想要相同的结果，即在MongoDB中将行透视到列而不聚合任何东西(到目前为止).

I want the same result i.e. pivot row to column without aggregating anything (as of now) in MongoDB.

该集合如下所示.这些是facebook页面属性的统计信息:

The collection looks something as below. These are statistics of facebook page properties:

timestamp | propName | propValue
--------------------------------
1371798000000 | page_fans | 100
--------------------------------
1371798000000 | page_posts | 50
--------------------------------
1371798000000 | page_stories | 25
--------------------------------

我需要像这样的答案

timestamp | page_fans | page_posts | page_stories
--------------------------------
1371798000000 | 100 | 50 | 25
--------------------------------

列名是预先确定的.它们不必动态生成.但是问题是如何在MongoDB中实现这一目标.

The column names are pre-determined. They don't have to be generated dynamically. But question is how to achieve this in MongoDB.

我认为聚合对于此目的毫无用处.我需要使用MapReduce吗?但是在那种情况下，我没什么可减少的吗?好吧，另一个选择可能是在代码中获取这些值并以编程语言进行操作，例如Java

I believe aggregation is of no use for this purpose. Do I need to use MapReduce? But in that case I have nothing to reduce I guess? Well another option could be fetching these values in code and do the manipulation in programming language e.g. Java

任何见解都会有所帮助.在此先感谢:)!!!

Any insights would be helpful. Thanks in advance :)!!!

编辑(基于Schaliasos的输入):

EDIT (Based on input from Schaliasos):

输入JSON:

{
        "_id" : ObjectId("51cd366644aeac654ecf8f75"),
        "name" : "page_storytellers",
        "pageId" : "512f993a44ae78b14a9adb85",
        "timestamp" : NumberLong("1371798000000"),
        "value" : NumberLong(30871),
        "provider" : "Facebook"
}
{
        "_id" : ObjectId("51cd366644aeac654ecf8f76"),
        "name" : "page_fans",
        "pageId" : "512f993a44ae78b14a9adb85",
        "timestamp" : NumberLong("1371798000000"),
        "value" : NumberLong(1291509),
        "provider" : "Facebook"
}
{
        "_id" : ObjectId("51cd366644aeac654ecf8f77"),
        "name" : "page_fan_adds",
        "pageId" : "512f993a44ae78b14a9adb85",
        "timestamp" : NumberLong("1371798000000"),
        "value" : NumberLong(2829),
        "provider" : "Facebook"
}

预期的输出JSON:

{
        "timestamp" : NumberLong("1371798000000"),
        "provider" : "Facebook",
        "page_storytellers" : NumberLong(30871),
        "page_fans" : NumberLong("1371798000000"),
        "page_fan_adds" : NumberLong("1371798000000")
}

推荐答案

我已经使用聚合完成了类似的事情.这可以帮忙吗?

I have done something like this using aggregation. Could this help ?

db.foo.insert({ timestamp: '1371798000000', propName: 'page_fans', propValue: 100})
db.foo.insert({ timestamp: '1371798000000', propName: 'page_posts', propValue: 25})
db.foo.insert({ timestamp: '1371798000000', propName: 'page_stories', propValue: 50})

db.foo.aggregate({ $group: { _id: '$timestamp', result: { $push: { 'propName': '$propName', 'propValue': '$propValue' } }}})

{
    "result" : [
        {
            "_id" : "1371798000000",
            "result" : [
                {
                    "propName" : "page_fans",
                    "propValue" : 100
                },
                {
                    "propName" : "page_posts",
                    "propValue" : 50
                },
                {
                    "propName" : "page_stories",
                    "propValue" : 25
                }
            ]
        }
    ],
    "ok" : 1
}

您可能会一直使用$sum运算符.请参见此处

You may want to use $sum operator along the way. See here

这篇关于将行旋转到MongoDB中的列的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！