[{"_id":{"$oid":"630f3c32c1a580642a9ff4a0"},"title":"This is a title","slug":"this-is-a-title","Post":"this is a post"}]

db.collection.update({},[{$set:{slug:{$concat:["$slug","-",{$toString:{$round:{$add:[{$multiply:[{$rand:{}},899999]},100000]}}}]}}}])