[{"key":1,"price":666},{"key":2,"price":300},{"key":3,"price":99}]

db.collection.aggregate([{$match:{price:{$gt:100}}},{$group:{_id:null,total:{$sum:"$key"},totalprice:{$sum:"$price"},max:{$max:"$price"},min:{$min:"$price"},avg:{$avg:"$price"},count:{$sum:1}}},{$project:{_id:0,/** Exclude _id field*/summary:{total:"$total",totalprice:"$totalprice",max:"$max",min:"$min",avg:"$avg",count:"$count"}}},{$sort:{summary:1}}])