Select entries which doesn't have specified key - mongodb

Question

Assume, that I have bunch of entries in a document:
db.document
and some of them doesn't have some key, let's say name. So we have two types of entries - with and without name.
{ "_id" : ObjectId("4dea81a8bd2bb0323800002d"), "fetched_at" : ISODate("2013-08-02T17:41:30Z"), "keyword" : "110770", "name" : "SOME NAME" }
{ "_id" : ObjectId("4dea81a8bd2bb0323800002a"), "fetched_at" : ISODate("2013-08-02T17:44:17Z"), "keyword" : "125176" }
I want to remove all entries without name property, because it makes my database incosistent. How can I do that? I tried with null and undefined but it doesn't works.

Answer 1

it's possible using $exists:
db.document.remove( { name : { $exists : false } } );

Answer 2

db.document.remove( { name : null } )
should work too. Example:
> db.document.insert({"fetched_at" : ISODate("2013-08-02T17:41:30Z"), "keyword" : "110770", "name" : "SOME NAME"})
> db.document.insert({"fetched_at" : ISODate("2013-08-02T17:44:17Z"), "keyword" : "125176" })
> db.document.insert({"fetched_at" : ISODate("2013-08-02T17:44:17Z"), "keyword" : "125176" })
> db.document.find().size()
3
> db.document.remove({name:null})
> db.document.find().size()
1
> db.document.find().pretty()
{
"_id" : ObjectId("520eac7e5d0ee1aa8515a550"),
"fetched_at" : ISODate("2013-08-02T17:41:30Z"),
"keyword" : "110770",
"name" : "SOME NAME"
}