_type

Each document indexed is associated with an id and a type. The type, when indexing, is automatically indexed into a _type field. By default, the _type field is indexed (but not analyzed) and not stored. This means that the _type field can be queried.

The _type field can be stored as well, for example:

{
    "tweet" : {
        "_type" : {"store" : true}
    }
}

The _type field can also not be indexed, and all the APIs will still work except for specific queries (term queries / filters) or faceting done on the _type field.

{
    "tweet" : {
        "_type" : {"index" : "no"}
    }
}