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ClickHouse/docs/en/query_language/dicts/external_dicts.md

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Sources for english documentation switched to Markdown. Edit page link is fixed too for both language versions of documentation.
2017-12-28 15:13:23 +00:00
<a name="dicts-external_dicts"></a>
# External dictionaries
You can add your own dictionaries from various data sources. The data source for a dictionary can be a local text or executable file, an HTTP(s) resource, or another DBMS. For more information, see "[Sources for external dictionaries](external_dicts_dict_sources.md#dicts-external_dicts_dict_sources)".
ClickHouse:
> - Fully or partially stores dictionaries in RAM.
- Periodically updates dictionaries and dynamically loads missing values. In other words, dictionaries can be loaded dynamically.
Some WIP on documentation refactoring (#2659) * Additional .gitignore entries * Merge a bunch of small articles about system tables into single one * Merge a bunch of small articles about formats into single one * Adapt table with formats to English docs too * Add SPb meetup link to main page * Move Utilities out of top level of docs (the location is probably not yet final) + translate couple articles * Merge MacOS.md into build_osx.md * Move Data types higher in ToC * Publish changelog on website alongside documentation * Few fixes for en/table_engines/file.md * Use smaller header sizes in changelogs * Group up table engines inside ToC * Move table engines out of top level too * Specificy in ToC that query language is SQL based. Thats a bit excessive, but catches eye. * Move stuff that is part of query language into respective folder * Move table functions lower in ToC * Lost redirects.txt update * Do not rely on comments in yaml + fix few ru titles * Extract major parts of queries.md into separate articles * queries.md has been supposed to be removed * Fix weird translation * Fix a bunch of links * There is only table of contents left * "Query language" is actually part of SQL abbreviation * Change filename in README.md too * fix mistype
2018-07-18 10:00:53 +00:00
The configuration of external dictionaries is located in one or more files. The path to the configuration is specified in the [dictionaries_config](../../operations/server_settings/settings.md#server_settings-dictionaries_config) parameter.
Sources for english documentation switched to Markdown. Edit page link is fixed too for both language versions of documentation.
2017-12-28 15:13:23 +00:00
Some WIP on documentation refactoring (#2659) * Additional .gitignore entries * Merge a bunch of small articles about system tables into single one * Merge a bunch of small articles about formats into single one * Adapt table with formats to English docs too * Add SPb meetup link to main page * Move Utilities out of top level of docs (the location is probably not yet final) + translate couple articles * Merge MacOS.md into build_osx.md * Move Data types higher in ToC * Publish changelog on website alongside documentation * Few fixes for en/table_engines/file.md * Use smaller header sizes in changelogs * Group up table engines inside ToC * Move table engines out of top level too * Specificy in ToC that query language is SQL based. Thats a bit excessive, but catches eye. * Move stuff that is part of query language into respective folder * Move table functions lower in ToC * Lost redirects.txt update * Do not rely on comments in yaml + fix few ru titles * Extract major parts of queries.md into separate articles * queries.md has been supposed to be removed * Fix weird translation * Fix a bunch of links * There is only table of contents left * "Query language" is actually part of SQL abbreviation * Change filename in README.md too * fix mistype
2018-07-18 10:00:53 +00:00
Dictionaries can be loaded at server startup or at first use, depending on the [dictionaries_lazy_load](../../operations/server_settings/settings.md#server_settings-dictionaries_lazy_load) setting.
Sources for english documentation switched to Markdown. Edit page link is fixed too for both language versions of documentation.
2017-12-28 15:13:23 +00:00
The dictionary config file has the following format:
```xml
<yandex>
<comment>An optional element with any content. Ignored by the ClickHouse server.</comment>
<!--Optional element. File name with substitutions-->
<include_from>/etc/metrika.xml</include_from>
English translation is updated.
2018-04-23 06:20:21 +00:00
Sources for english documentation switched to Markdown. Edit page link is fixed too for both language versions of documentation.
2017-12-28 15:13:23 +00:00
<dictionary>
English translation is updated.
2018-04-23 06:20:21 +00:00
<!-- Dictionary configuration -->
Sources for english documentation switched to Markdown. Edit page link is fixed too for both language versions of documentation.
2017-12-28 15:13:23 +00:00
</dictionary>
English translation is updated.
2018-04-23 06:20:21 +00:00
Sources for english documentation switched to Markdown. Edit page link is fixed too for both language versions of documentation.
2017-12-28 15:13:23 +00:00
...
<dictionary>
<!-- Dictionary configuration -->
</dictionary>
</yandex>
```
You can [configure](external_dicts_dict.md#dicts-external_dicts_dict) any number of dictionaries in the same file. The file format is preserved even if there is only one dictionary (i.e. `<yandex><dictionary> <!--configuration -> </dictionary></yandex>` ).
See also "[Functions for working with external dictionaries](../functions/ext_dict_functions.md#ext_dict_functions)".
WIP on documentation (#2692) * Additional .gitignore entries * Merge a bunch of small articles about system tables into single one * Merge a bunch of small articles about formats into single one * Adapt table with formats to English docs too * Add SPb meetup link to main page * Move Utilities out of top level of docs (the location is probably not yet final) + translate couple articles * Merge MacOS.md into build_osx.md * Move Data types higher in ToC * Publish changelog on website alongside documentation * Few fixes for en/table_engines/file.md * Use smaller header sizes in changelogs * Group up table engines inside ToC * Move table engines out of top level too * Specificy in ToC that query language is SQL based. Thats a bit excessive, but catches eye. * Move stuff that is part of query language into respective folder * Move table functions lower in ToC * Lost redirects.txt update * Do not rely on comments in yaml + fix few ru titles * Extract major parts of queries.md into separate articles * queries.md has been supposed to be removed * Fix weird translation * Fix a bunch of links * There is only table of contents left * "Query language" is actually part of SQL abbreviation * Change filename in README.md too * fix mistype * s/formats\/interfaces/interfaces\/formats/g * Remove extra clarification from header as it was too verbose, probably making it a bit more confusing * Empty article was supposed to be hidden * At least change incorrect title * Move special links to the bottom of nav and slightly highlight them * Skip hidden pages in bottom navigation too * Make front page of documentation to be part of Introduction * Make tables in introduction somewhat readable + move abbreviation definitions earlier * Some introduction text refactoring * Some docs introduction refactoring * Use admonitions instead of divs * Additional .gitignore * Treat .gif as images too * Clarify ToC item
2018-07-20 17:35:34 +00:00
!!! attention
You can convert values for a small dictionary by describing it in a `SELECT` query (see the [transform](../functions/other_functions.md#other_functions-transform) function). This functionality is not related to external dictionaries.
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