Each document indexed is associated with a _type (see the section called “Mapping Typesedit”) and an_id. The _id field is not indexed as its value can be derived automatically from the _uid field.

The value of the _id field is accessible in certain queries (term, terms, match, query_string,simple_query_string), but not in aggregations, scripts or when sorting, where the _uid field should be used instead:

# Example documents
PUT my_index/my_type/1 { "text": "Document with ID 1" } PUT my_index/my_type/2&refresh=true { "text": "Document with ID 2" } GET my_index/_search { "query": { "terms": { "_id": [ "1", "2" ]  } } }