Does the elasticsearch ID have to be unique to a type or to the index?

Question

Elasticsearch allows you to store a _type along with the _index. I was wondering if I were to provide my own _id should it be unique across the index?

Answer 1

It should be unique together

PUT so
PUT /so/t1/1
{}
PUT /so/t2/1
{}
GET /so/_search

{
   "took": 1,
   "timed_out": false,
   "_shards": {
      "total": 5,
      "successful": 5,
      "failed": 0
   },
   "hits": {
      "total": 2,
      "max_score": 1,
      "hits": [
         {
            "_index": "so",
            "_type": "t2",
            "_id": "1",
            "_score": 1,
            "_source": {}
         },
         {
            "_index": "so",
            "_type": "t1",
            "_id": "1",
            "_score": 1,
            "_source": {}
         }
      ]
   }
}

And the reason for that: you'd never get documents by index w/o knowing doctype, and querying ES with index-wide query will return documents including their types and indexes.