Elasticsearch terms aggregation by strings in an array

I think all you're missing is "states.raw" in your aggregation (note that, since no analyzer is specified, the "states" field is analyzed with the standard analyzer; the sub-field "raw" is "not_analyzed"). Though your mapping might bear looking at as well. When I tried your mapping against ES 2.0 I got some errors, but this worked:

PUT /test_index{   "mappings": {      "doc": {         "properties": {            "states": {               "type": "string",               "fields": {                  "raw": {                     "type": "string",                     "index": "not_analyzed"                  }               }            }         }      }   }}

Then I added a couple of docs:

POST /test_index/doc/_bulk{"index":{"_id":1}}{"states":["New York","New Jersey","California"]}{"index":{"_id":2}}{"states":["New York","North Carolina","North Dakota"]}

And this query seems to do what you want:

POST /test_index/_search{    "size": 0,     "aggs" : {        "states" : {            "terms" : {                 "field" : "states.raw",                "size": 10            }        }    }}

returning:

{   "took": 1,   "timed_out": false,   "_shards": {      "total": 1,      "successful": 1,      "failed": 0   },   "hits": {      "total": 2,      "max_score": 0,      "hits": []   },   "aggregations": {      "states": {         "doc_count_error_upper_bound": 0,         "sum_other_doc_count": 0,         "buckets": [            {               "key": "New York",               "doc_count": 2            },            {               "key": "California",               "doc_count": 1            },            {               "key": "New Jersey",               "doc_count": 1            },            {               "key": "North Carolina",               "doc_count": 1            },            {               "key": "North Dakota",               "doc_count": 1            }         ]      }   }}

Here's the code I used to test it:

http://sense.qbox.io/gist/31851c3cfee8c1896eb4b53bc1ddd39ae87b173e