# _uid field 每個索引的文檔都與一個?**[_type](https://www.elastic.co/guide/en/elasticsearch/reference/5.3/mapping-type-field.html)**（請參見“**[Mapping Types](https://www.elastic.co/guide/en/elasticsearch/reference/5.3/mapping.html#mapping-type)[edit](https://github.com/elastic/elasticsearch/edit/5.3/docs/reference/mapping.asciidoc)**”一節）和一個?**[_id](https://www.elastic.co/guide/en/elasticsearch/reference/5.3/mapping-id-field.html)?**相關聯。 這些值組合為?**{type}＃{id}?**并作為?**_uid?**字段編入索引。 該**?_uid?**字段的值可以在?**queries**（查詢），**aggregations**（聚合），**scripts**（腳本）以及?**sorting**（排序）時訪問 :? | `# Example documents` `curl -XPUT?``'localhost:9200/my_index/my_type/1?pretty'`?`-H?``'Content-Type: application/json'`?`-d'` `{` `"text"``:?``"Document with ID 1"` `}` `'` `curl -XPUT?``'localhost:9200/my_index/my_type/2?refresh=true&pretty'`?`-H?``'Content-Type: application/json'`?`-d'` `{` `"text"``:?``"Document with ID 2"` `}` `'` `curl -XGET?``'localhost:9200/my_index/_search?pretty'`?`-H?``'Content-Type: application/json'`?`-d'` `{` `"query"``: {` `"terms"``: {` `"_uid"``: [?``"my_type#1"``,?``"my_type#2"`?`] # 1` `}` `},` `"aggs"``: {` `"UIDs"``: {` `"terms"``: {` `"field"``:?``"_uid"``,?``# 2` `"size"``: 10` `}` `}` `},` `"sort"``: [` `{` `"_uid"``: {?``# 3` `"order"``:?``"desc"` `}` `}` `],` `"script_fields"``: {` `"UID"``: {` `"script"``: {` `"lang"``:?``"painless"``,` `"inline"``:?``"doc['_uid']"`?`# 4` `}` `}` `}` `}` `'` | | 1 | 在?**_uid?**字段上查詢 (也可以參考?**[ids?query](https://www.elastic.co/guide/en/elasticsearch/reference/5.3/query-dsl-ids-query.html)**) | | 2 | 在?**_uid?**字段上聚合 | | 3 | 在?**_uid?**字段上排序 | | 4 | 在腳本中訪問?**_uid?**字段 |