Add hint for Array mappings (simple and complex types)

[jeffsteinmetz]

It seems like a "hint" would be helpful to projects like elasticsearch-hadoop / spark if the mappings exposed when a json array is expected.
elastic/elasticsearch-hadoop#484
elastic/elasticsearch-hadoop#482

It may also be useful for tools like Kibana.
A hint such as "array": true

• (side note, this hint is unrelated to nested object mapping via "type: "nested": Similar to but really more of a hint vs. a nested mapping that actually changes how it is indexed.)

such as

  "mappings": {
    "foo": {
      "properties": {
        "bar": {
          "array": true, 
          "properties": {
            "name":    { "type": "string"  },
            "scores":   { "type": "string", "array": true }
          }
        }
      }
    }
  }
}

which would provide hints to json documents such as

{"foo" : { "bar" : ["name": "jeff", "scores": [10,20,30], "name" : "bob", "scores" : [5,10] ] } }

[clintongormley]

Hi @jeffsteinmetz

Any field in Elasticsearch can be an array or a single value, so I don't like adding the array parameter as a hint. However, this kind of application specific extra mapping info can be stored in the mapping in the _meta field.