Question

查询：

db.environments.aggregate(
[{$match:{customer:"CustomerName"}},
{$group:{_id:{environment: "$environment",
cpu_oversubscription:"$cpu_oversubscription",
memory_oversubscription:"$memory_oversubscription"}}} ])

当我运行查询时，只显示环境和CPU_oversubcription字段，不显示内存字段。

这是我得到的输出：

[{"_id":{"environment":"V&B","cpu_oversubscription":1}}

当我运行db.environments.find()时，我会看到所有字段

[{"_id":{"environment":"V&B","cpu_oversubscription":1,"memory_oversubscription":1,"customer":"CustomerName"}}

我的查询有什么问题？

修改：完全查询

Environment.aggregate([{$match:{customer:req.query.customer}},{$group:{_id:{environment: "$environment",cpu_oversubscription:"$cpu_oversubscription",memory_oversubscription:"$memory_oversubscription",}}} ])

查询的确切结果

{ "_id" : { "environment" : "1", "cpu_oversubscription" : 1 } }
{ "_id" : { "environment" : "2", "cpu_oversubscription" : 4 } }
{ "_id" : { "environment" : "3", "cpu_oversubscription" : 4 } }
{ "_id" : { "environment" : "4", "cpu_oversubscription" : 4 } }
{ "_id" : { "environment" : "5", "cpu_oversubscription" : 4 } }
{ "_id" : { "environment" : "6", "cpu_oversubscription" : 1 } }
{ "_id" : { "environment" : "7", "cpu_oversubscription" : 1 } }
{ "_id" : { "environment" : "8", "cpu_oversubscription" : 1 } }
{ "_id" : { "environment" : "9", "cpu_oversubscription" : 4 } }
{ "_id" : { "environment" : "10", "cpu_oversubscription" : 4 } }

db.environments.find（）的确切结果（仅限第一个结果）

{ "_id" : ObjectId("560a5139b56a71ea60890201"), "customer" : "CustomerName", "environment" : "1", "memory_oversubcription" : 1, "cpu_oversubscription" : 1 }

Answer 1

正如@Yogesh所说，您的数据中存在拼写错误。这解决了你的问题。

尽管如此，您不需要此查询的聚合框架：使用投影的 find 会更有效率：

db.environments.find({ "customer" : "CustomerName" }, 
                     { _id : 0, "environment" : 1,
                       "memory_oversubscription" : 1, 
                       "cpu_oversubscription" : 1
                     })

结果将是：

{ 
  "environment" : "1", 
  "memory_oversubscription" : 1,
  "cpu_oversubscription" : 1 
}

如果由于某些原因你真的想在_id字段下得到结果，那么$ project会更好：

db.environments.aggregate([
  {$match:{"customer" : "CustomerName"}},
  {$project: 
    {_id : 
      {"environment" : "$environment",
       "memory_oversubscription" : "$memory_oversubscription", 
       "cpu_oversubscription" : "$cpu_oversubscription"}
    }
  }
]);

结果：

{ "_id" : { "environment" : "1", 
            "memory_oversubscription" : 1, 
            "cpu_oversubscription" : 1 } 
}

对我没有意义，但也许它适合你： - ）。

MongoDB - 字段未显示在Aggregate中

1 个答案: