Currently we can do:

foo=db.kg.findAndModify({query:

{"dogs":2}

,update:{$inc:

{"dogs":1}

}})

{ "_id" : ObjectId("4bc665954c25a502cc9c76ef"), "dogs" : 2 }

foo

{ "_id" : ObjectId("4bc665954c25a502cc9c76ef"), "dogs" : 2 }

db.kg.find()

{ "_id" : ObjectId("4bc665954c25a502cc9c76ef"), "dogs" : 3 }

I think this would be nicer:

foo=db.kg.update({},{$inc:{"dogs":1}} )
foo

{"dogs":4}

and perhaps even:

foo=db.kg.update({},{$inc{"dogs":1}},{$inc{"cats":1}})
foo

{"dogs":5,"cats":2}

Returning the incremented value allows applications to use the newly generated value