mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-10-09 18:10:48 +00:00
2e1f6bc56d
* replace exit with assert in test_single_page * improve save_raw_single_page docs option * More grammar fixes * "Built from" link in new tab * fix mistype * Example of include in docs * add anchor to meeting form * Draft of translation helper * WIP on translation helper * Replace some fa docs content with machine translation * add normalize-en-markdown.sh * normalize some en markdown * normalize some en markdown * admonition support * normalize * normalize * normalize * support wide tables * normalize * normalize * normalize * normalize * normalize * normalize * normalize * normalize * normalize * normalize * normalize * normalize * normalize * lightly edited machine translation of introdpection.md * lightly edited machhine translation of lazy.md * WIP on translation utils * Normalize ru docs * Normalize other languages * some fixes * WIP on normalize/translate tools * add requirements.txt * [experimental] add es docs language as machine translated draft * remove duplicate script * Back to wider tab-stop (narrow renders not so well)
15 lines
771 B
Markdown
15 lines
771 B
Markdown
# 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](../syntax.md#null) values can’t be stored in a dictionary.
|
||
|
||
ClickHouse supports:
|
||
|
||
- [Built-in dictionaries](internal_dicts.md#internal_dicts) with a specific [set of functions](../functions/ym_dict_functions.md).
|
||
- [Plug-in (external) dictionaries](external_dicts.md) with a [set of functions](../functions/ext_dict_functions.md).
|
||
|
||
[Original article](https://clickhouse.tech/docs/en/query_language/dicts/) <!--hide-->
|