_index
fieldedit
When performing queries across multiple indexes, it is sometimes desirable to
add query clauses that are associated with documents of only certain indexes.
The _index
field allows matching on the index a document was indexed into.
Its value is accessible in certain queries and aggregations, and when sorting
or scripting:
PUT index_1/_doc/1 { "text": "Document in index 1" } PUT index_2/_doc/2?refresh=true { "text": "Document in index 2" } GET index_1,index_2/_search { "query": { "terms": { "_index": ["index_1", "index_2"] } }, "aggs": { "indices": { "terms": { "field": "_index", "size": 10 } } }, "sort": [ { "_index": { "order": "asc" } } ], "script_fields": { "index_name": { "script": { "lang": "painless", "source": "doc['_index']" } } } }
Querying on the |
|
Aggregating on the |
|
Sorting on the |
|
Accessing the |
The _index
field is exposed virtually — it is not added to the Lucene index
as a real field. This means that you can use the _index
field in a term
or
terms
query (or any query that is rewritten to a term
query, such as the
match
, query_string
or simple_query_string
query), as well as prefix
and wildcard
queries. However, it does not support regexp
and fuzzy
queries.
Queries on the _index
field accept index aliases in addition to concrete
index names.
When specifying a remote index name such as cluster_1:index_3
, the
query must contain the separator character :
. For example, a wildcard
query
on cluster_*:index_3
would match documents from the remote index. However, a
query on cluster*index_1
is only matched against local indices, since no
separator is present. This behavior aligns with the usual resolution rules for
remote index names.