Sorting with undefined values

sort.sh

curl -XDELETE 'localhost:9200/sort'

curl -XPOST 'localhost:9200/sort'

curl -XPUT 'localhost:9200/sort/sort/1' -d '
{
  "num" : 1
}
'
curl -XPUT 'localhost:9200/sort/sort/2' -d '
{
  "num" : 2
}
'

curl -XPUT 'localhost:9200/sort/sort/3' -d '
{
   "test" : "Hello World"
}
'

curl -XGET 'localhost:9200/_refresh'

curl -XPOST 'localhost:9200/sort/_search?pretty' -d '
{
  "query": {
    "match_all" : {}
  },
  "sort" : [
     { "num" : { "order" : "asc" } }
  ]

}'

curl -XPOST 'localhost:9200/sort/_search?pretty' -d '
{
  "query": {
    "match_all" : {}
  },
  "sort" : [
     { "num" : { "order" : "desc" } }
  ]

}'