47 lines
1.2 KiB
Plaintext
47 lines
1.2 KiB
Plaintext
[[mapping-id-field]]
|
|
=== `_id` field
|
|
|
|
Each document has an `_id` that uniquely identifies it, which is indexed
|
|
so that documents can be looked up either with the <<docs-get,GET API>> or the
|
|
<<query-dsl-ids-query,`ids` query>>.
|
|
|
|
The value of the `_id` field is accessible in certain queries (`term`,
|
|
`terms`, `match`, `query_string`, `simple_query_string`).
|
|
|
|
[source,console]
|
|
--------------------------
|
|
# Example documents
|
|
PUT my_index/_doc/1
|
|
{
|
|
"text": "Document with ID 1"
|
|
}
|
|
|
|
PUT my_index/_doc/2?refresh=true
|
|
{
|
|
"text": "Document with ID 2"
|
|
}
|
|
|
|
GET my_index/_search
|
|
{
|
|
"query": {
|
|
"terms": {
|
|
"_id": [ "1", "2" ] <1>
|
|
}
|
|
}
|
|
}
|
|
--------------------------
|
|
|
|
<1> Querying on the `_id` field (also see the <<query-dsl-ids-query,`ids` query>>)
|
|
|
|
The value of the `_id` field is also accessible in aggregations or for sorting,
|
|
but doing so is discouraged as it requires to load a lot of data in memory. In
|
|
case sorting or aggregating on the `_id` field is required, it is advised to
|
|
duplicate the content of the `_id` field in another field that has `doc_values`
|
|
enabled.
|
|
|
|
|
|
[NOTE]
|
|
==================================================
|
|
`_id` is limited to 512 bytes in size and larger values will be rejected.
|
|
==================================================
|