mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-10-17 22:10:54 +00:00
dba72d73fe
* enbaskakova-DOCSUP-652 (#101)
* "docs(orNull&orDefault): Functions 'orNull&orDefault' have been edited"
* "docs(orNull&orDefault): Functions 'orNull&orDefault' have been edited"
* "docs(orNull&orDefault): Functions 'orNull&orDefault' have been edited"
* Update docs/en/sql_reference/aggregate_functions/combinators.md
Co-Authored-By: BayoNet <da-daos@yandex.ru>
* Update docs/en/sql_reference/aggregate_functions/combinators.md
Co-Authored-By: BayoNet <da-daos@yandex.ru>
* Update docs/en/sql_reference/aggregate_functions/combinators.md
Co-Authored-By: BayoNet <da-daos@yandex.ru>
* Update docs/en/sql_reference/aggregate_functions/combinators.md
Co-Authored-By: BayoNet <da-daos@yandex.ru>
* Update docs/en/sql_reference/aggregate_functions/combinators.md
Co-Authored-By: BayoNet <da-daos@yandex.ru>
* "docs(orNull&orDefault): Functions 'orNull&orDefault' have been edited"
* "docs(orNull&orDefault): Functions 'orNull&orDefault' have been edited"
* "docs(orNull&orDefault): Functions 'orNull&orDefault' have been edited"
Co-authored-by: elenbaskakova <elenbaskakova@yandex-team.ru>
Co-authored-by: BayoNet <da-daos@yandex.ru>
* Revert "enbaskakova-DOCSUP-652 (#101)" (#107)
This reverts commit 639fee7610.
* CLICKHOUSEDOCS-624: Fixed links. Was 60, became 13.
* CLICKHOUSEDOCS-624: Finished fix links in Enlish version.
* CLICKHOUSEDOCS-624: Fixed RU links
Co-authored-by: elenaspb2019 <47083263+elenaspb2019@users.noreply.github.com>
Co-authored-by: elenbaskakova <elenbaskakova@yandex-team.ru>
Co-authored-by: Sergei Shtykov <bayonet@yandex-team.ru>
21 lines
954 B
Markdown
21 lines
954 B
Markdown
---
|
||
toc_folder_title: Dictionaries
|
||
toc_priority: 35
|
||
toc_title: Introduction
|
||
---
|
||
|
||
# Dictionaries {#dictionaries}
|
||
|
||
A dictionary is a mapping (`key -> attributes`) that is convenient for various types of reference lists.
|
||
|
||
ClickHouse supports special functions for working with dictionaries that can be used in queries. It is easier and more efficient to use dictionaries with functions than a `JOIN` with reference tables.
|
||
|
||
[NULL](../../sql-reference/syntax.md#null-literal) values can’t be stored in a dictionary.
|
||
|
||
ClickHouse supports:
|
||
|
||
- [Built-in dictionaries](internal-dicts.md#internal_dicts) with a specific [set of functions](../../sql-reference/functions/ym-dict-functions.md).
|
||
- [Plug-in (external) dictionaries](external-dictionaries/external-dicts.md#dicts-external-dicts) with a [set of functions](../../sql-reference/functions/ext-dict-functions.md).
|
||
|
||
[Original article](https://clickhouse.tech/docs/en/query_language/dicts/) <!--hide-->
|