mongodb分组统计

db.getCollection('dataOperateLog').aggregate([
    {$match:{operateType:'LOGIN',operateTime:{'$gt':ISODate("2017-01-01T00:00:00.000Z")}}},
    {$group: {  
        _id: {  
            "params": "$params"  
        },   
     count: {$sum: 1}}  
    },  
    {$sort: {"count": -1}}  
]);