mongodb - mongo 是否提供解构大型数据集文档数组的功能？

Question

类似于 map/reduce 但相反。 mongo 是否有重新格式化数据的方法。我有以下格式的集合。

{ 
  {"token-id" : "LKJ8_lkjsd"
    "data": [
               {"views":100, "Date": "2015-01-01"},
               {"views":200, "Date": "2015-01-02"},
               {"views":300, "Date": "2015-01-03"},
               {"views":300, "Date": "2015-01-03"}
            ]
  }
}

我想将整个集合处理成一种新格式。其中每个时间序列数据点都是其文档映射到 ID，希望使用类似于 map reduce 的一些固有的 mongo 功能。如果没有；我希望有一个我们可以做到这一点的策略。

{
  { "token-id" : "LKJ8_lkjsd", "views": 100, "Date" : "2015-01-01"},
  { "token-id" : "LKJ8_lkjsd", "views": 200, "Date" : "2015-01-01"},
  { "token-id" : "LKJ8_lkjsd", "views": 300, "Date" : "2015-01-01"}
}

Answer 1

The aggregate command can return results as a cursor or store the results in a collection, which are not subject to the size limit. The db.collection.aggregate() returns a cursor and can return result sets of any size.

 var result = db.test.aggregate( [ { $unwind : "$data" }, {$project: {_id:0, "token-id":1, "data":1}}])

    for(result.hasNext()){
     db.collection.insert(result.next());
    }