如何在mongodb中找到前5个值?并且不应包含相同的值 [英] How to find top 5 values in mongodb ? and should not contain same value

问题描述

我在DB中有这样的数据

I have data in DB something like this

    [
       { Appname:ktr, softcount:10 ,timeStamp:1 },
       { Appname:rsr, soscount:8,timeStamp:2 },
       { Appname:ktr, softcount:9 ,timeStamp:3},
       { Appname:ssl, softcount:6,timeStamp:4},
       { Appname:ktr, softcount:7,timeStamp:5 },
       { Appname:ppr, softcount:5,timeStamp:6},
       { Appname:crs, softcount:4,timeStamp:7 },
       ............

    ] 

此处Appname键将包含未知值. Appname可能是任何东西.

here Appname key will contain the value which is unknown value . Appname might be anything .

我需要根据时间范围找到前5个软计数记录，并且也不应包含相同的Appname

I need to find top 5 softcount record based on the timerange and that too should not contain the same Appname

要找到前5个值，我已使用此查询

To find the top 5 values , I have used this query

  db.collection.find({timeStamp : { $gte : startTime, $lte :endTime}}).sort({'softcount':-1}).count(5) 

此处startTime为1，endTime为7

here startTime is 1 and endTime is 7

给出前5个softcount记录，但记录包含相同的Appname.

it is give top 5 softcount record but record contains same Appname . so

我希望从db中获得类似这样的结果

i want the result something like this from db

[
  {Appname:ktr,softcount:10,timeStamp:1},
  {Appname:rsr,softcount:8,timeStamp:2},
  {Appname:ssl,softcount:6,timeStamp:4},
  {Appname:ppr,softcount:5,timeStamp:6},
  {Appname:crs,softcount:4,timeStamp:7}
]

在此结果中Appnames不同，它不包含相同的Appname.

in this result Appnames are not same it does not contain the same Appname .

是否可以编写mongodb查询?

is it possible to write mongodb query ?

要获得以上记录的查询是什么?

what is the query to get above record ?

推荐答案

好，您可以使用聚合管道以想要查看的格式对数据进行分组和投影.

Well, you can use aggregation pipeline to group and project data in format you want to see.

db.col.aggregate([
{$group:{_id:"$Appname", softcount:{$max:"$softcount"}}},
{$project:{_id:0, "Appname":"$_id", softcount:1}},
{$sort:{softcount:-1}},
{$limit: 5}
])

如果输入的内容是您在问题中提到的内容，它将打印以下结果.

this will print following result, provided input is what you mentioned in your question.

{ 
    "softcount" : 10.0, 
    "Appname" : "ktr"
}
{ 
    "softcount" : 8.0, 
    "Appname" : "rsr"
}
{ 
    "softcount" : 6.0, 
    "Appname" : "ssl"
}
{ 
    "softcount" : 5.0, 
    "Appname" : "ppr"
}
{ 
    "softcount" : 4.0, 
    "Appname" : "crs"
}

您可以在 https://docs.mongodb.org/manual/上了解有关MongoDB聚合框架的更多信息.聚合/

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