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* split up select.md * array-join.md basic refactoring * distinct.md basic refactoring * format.md basic refactoring * from.md basic refactoring * group-by.md basic refactoring * having.md basic refactoring * additional index.md refactoring * into-outfile.md basic refactoring * join.md basic refactoring * limit.md basic refactoring * limit-by.md basic refactoring * order-by.md basic refactoring * prewhere.md basic refactoring * adjust operators/index.md links * adjust sample.md links * adjust more links * adjust operatots links * fix some links * adjust aggregate function article titles * basic refactor of remaining select clauses * absolute paths in make_links.sh * run make_links.sh * remove old select.md locations * translate docs/es * translate docs/fr * translate docs/fa * remove old operators.md location * change operators.md links * adjust links in docs/es * adjust links in docs/es * minor texts adjustments * wip * update machine translations to use new links * fix changelog * es build fixes * get rid of some select.md links * temporary adjust ru links * temporary adjust more ru links * improve curly brace handling * adjust ru as well * fa build fix * ru link fixes * zh link fixes * temporary disable part of anchor checks
63 lines
2.9 KiB
Markdown
63 lines
2.9 KiB
Markdown
---
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machine_translated: true
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machine_translated_rev: 72537a2d527c63c07aa5d2361a8829f3895cf2bd
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toc_priority: 39
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toc_title: "\u6982\u8FF0"
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---
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# 外部字典 {#dicts-external-dicts}
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您可以从各种数据源添加自己的字典。 字典的数据源可以是本地文本或可执行文件、HTTP(s)资源或其他DBMS。 有关详细信息，请参阅 “[外部字典的来源](external-dicts-dict-sources.md)”.
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ClickHouse:
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- 完全或部分存储在RAM中的字典。
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- 定期更新字典并动态加载缺失的值。 换句话说，字典可以动态加载。
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- 允许创建外部字典与xml文件或 [DDL查询](../../statements/create.md#create-dictionary-query).
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外部字典的配置可以位于一个或多个xml文件中。 配置的路径在指定 [dictionaries\_config](../../../operations/server-configuration-parameters/settings.md#server_configuration_parameters-dictionaries_config) 参数。
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字典可以在服务器启动或首次使用时加载，具体取决于 [dictionaries\_lazy\_load](../../../operations/server-configuration-parameters/settings.md#server_configuration_parameters-dictionaries_lazy_load) 设置。
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该 [字典](../../../operations/system-tables.md#system_tables-dictionaries) 系统表包含有关在服务器上配置的字典的信息。 对于每个字典，你可以在那里找到:
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- 字典的状态。
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- 配置参数。
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- 度量指标，如为字典分配的RAM量或自成功加载字典以来的查询数量。
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字典配置文件具有以下格式:
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``` xml
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<yandex>
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<comment>An optional element with any content. Ignored by the ClickHouse server.</comment>
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<!--Optional element. File name with substitutions-->
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<include_from>/etc/metrika.xml</include_from>
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<dictionary>
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<!-- Dictionary configuration. -->
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<!-- There can be any number of <dictionary> sections in the configuration file. -->
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</dictionary>
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</yandex>
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```
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你可以 [配置](external-dicts-dict.md) 同一文件中的任意数量的字典。
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[字典的DDL查询](../../statements/create.md#create-dictionary-query) 在服务器配置中不需要任何其他记录。 它们允许使用字典作为一流的实体，如表或视图。
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!!! attention "注意"
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您可以通过在一个小字典中描述它来转换小字典的值 `SELECT` 查询（见 [变换](../../../sql-reference/functions/other-functions.md) 功能）。 此功能与外部字典无关。
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## 另请参阅 {#ext-dicts-see-also}
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- [配置外部字典](external-dicts-dict.md)
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- [在内存中存储字典](external-dicts-dict-layout.md)
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- [字典更新](external-dicts-dict-lifetime.md)
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- [外部字典的来源](external-dicts-dict-sources.md)
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- [字典键和字段](external-dicts-dict-structure.md)
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- [使用外部字典的函数](../../../sql-reference/functions/ext-dict-functions.md)
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[原始文章](https://clickhouse.tech/docs/en/query_language/dicts/external_dicts/) <!--hide-->
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