jsbin.luveqe.js

db.results.aggregate([
    {
        $match: { 
            $and:[   
                    {
                        "profile.Zend_Http_Client_Adapter_Socket::read==>fgets": {
                        "$exists": true }
                    },
                    {
                    "profile.main().wt": {
                        $lte: 10000000 }
                    }
                  ]
                }
     },
    {
        $group: {
            "_id": null,
            "count":{$sum:1},
            "fgetsAvg": {
                $avg: "$profile.Zend_Http_Client_Adapter_Socket::read==>fgets.wt"
            },
            "mainAvg" :{
                 $avg: "$profile.main().wt"
            }, 
        }
    }
    ])