Meta-Fields（元字段） · Elasticsearch 5.4 中文文檔

# Meta-Fields（元字段）原文鏈接 : [https://www.elastic.co/guide/en/elasticsearch/reference/5.3/mapping-fields.html](https://www.elastic.co/guide/en/elasticsearch/reference/5.3/mapping-fields.html) 譯文鏈接 : [http://www.apache.wiki/pages/viewpage.action?pageId=9405203](http://www.apache.wiki/pages/viewpage.action?pageId=9405203) 貢獻者 : [朱彥安](/display/~zhuyanan)，[ApacheCN](/display/~apachecn)，[Apache中文網](/display/~apachechina) 每個文檔都有與之關聯的元數據，比如?`**_index**，``**[_type](https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-type-field.html "_type field")?**和?`**`_id?`**元字段。當創建 **mapping** **type**（映射類型）時，可以自定義一些這些元字段的行為。 ### ?Identity meta-fields（身份的元字段） | [_index](https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-index-field.html) | 文檔所屬的索引。 | | [_uid](https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-uid-field.html) | 復合字段包含了**_type?**和 **_id** 。 | | [_type](https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-type-field.html) | 文檔的 [mapping type（映射類型）](https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping.html#mapping-type) 。 | | [_id](https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-id-field.html) | 文檔 ID。 | ### ?Document source meta-fields（文檔源的元字段） [`_source`](https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-source-field.html "_source field") 原始的 **JSON?**字符串表示文檔的正文。 ?[`_size`](https://www.elastic.co/guide/en/elasticsearch/plugins/5.3/mapper-size.html) ?**_source?**字段的大小（以字節為單位），由?[mapper-size](https://www.elastic.co/guide/en/elasticsearch/plugins/5.3/mapper-size.html)?插件提供。 ### ?Indexing meta-fields（索引的元字段） [`_all`](https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-all-field.html "_all field") 一個索引其他全部字段值的全能字段。 ?[`_field_names`](https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-field-names-field.html "_field_names field") ?文檔中包含非空值的所有字段。 ### Routing meta-fields（路由的元字段） [`_parent`](https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-parent-field.html "_parent field") 用于創建兩個映射類型之間的父子關系。 [`_routing`](https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-routing-field.html "_routing field") 將文檔路由到特定分片的自定義路由值。 ### ?Other meta-field（其他的元字段） [`_meta`](https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-meta-field.html "_meta field") ?特定應用的元數據。