Docs: Document special case for type parameter requirement for _mget

[ppf2]

The current documentation (http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/docs-multi-get.html#docs-multi-get) indicates that type is optional in the _mget request.

Per #6633, in the case of multiple types sharing the same ID, in order for _mget to fetch back documents sharing the same ID across types, a _type+_id parameter have to be specified (i.e. cannot simply specify _id to fetch documents across types sharing the same id).

GET /sameid/_mget/
{
  "docs" : [
        {
            "_type":"typeA",
            "_id" : "1"
        },
        {
            "_type":"typeB",
            "_id" : "1"
        }
    ]
}

Would be nice to add this as a special case in the documentation for _mget.

[dadoonet]

Agreed. May be with a link to http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/docs-get.html#type ?

[clintongormley]

@ppf2 want to send a PR?

[clintongormley]

@dadoonet your commit breaks the docs build because you're using an ID which is not unique across the docs, ie [[type]]

Please fix