ClickHouse/docs/en/query_language/dicts/index.md
Ivan Blinkov 0a4a5b36cc
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 13:00:53 +03:00

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Dictionaries

A dictionary is a mapping (key -> attributes) that can be used in a query as functions. You can think of this as a more convenient and efficient type of JOIN with dimension tables.

There are built-in (internal) and add-on (external) dictionaries.