ClickHouse/docs/ru/operations/table_engines/dictionary.md
Ivan Blinkov 16ca492938
WIP on docs (#3813)
* CLICKHOUSE-4063: less manual html @ index.md

* CLICKHOUSE-4063: recommend markdown="1" in README.md

* CLICKHOUSE-4003: manually purge custom.css for now

* CLICKHOUSE-4064: expand <details> before any print (including to pdf)

* CLICKHOUSE-3927: rearrange interfaces/formats.md a bit

* CLICKHOUSE-3306: add few http headers

* Remove copy-paste introduced in #3392

* Hopefully better chinese fonts #3392

* get rid of tabs @ custom.css

* Apply comments and patch from #3384

* Add jdbc.md to ToC and some translation, though it still looks badly incomplete

* minor punctuation

* Add some backlinks to official website from mirrors that just blindly take markdown sources

* Do not make fonts extra light

* find . -name '*.md' -type f | xargs -I{} perl -pi -e 's//g' {}

* find . -name '*.md' -type f | xargs -I{} perl -pi -e 's/ sql/g' {}

* Remove outdated stuff from roadmap.md

* Not so light font on front page too

* Refactor Chinese formats.md to match recent changes in other languages

* Update some links on front page

* Remove some outdated comment

* Add twitter link to front page

* More front page links tuning

* Add Amsterdam meetup link

* Smaller font to avoid second line

* Add Amsterdam link to README.md

* Proper docs nav translation

* Back to 300 font-weight except Chinese

* fix docs build

* Update Amsterdam link

* remove symlinks

* more zh punctuation

* apply lost comment by @zhang2014

* Apply comments by @zhang2014 from #3417

* Remove Beijing link

* rm incorrect symlink

* restore content of docs/zh/operations/table_engines/index.md

* CLICKHOUSE-3751: stem terms while searching docs

* CLICKHOUSE-3751: use English stemmer in non-English docs too

* CLICKHOUSE-4135 fix

* Remove past meetup link

* Add blog link to top nav

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* Add form link to front page + refactor some texts

* couple markup fixes

* minor

* Introduce basic ODBC driver page in docs

* More verbose 3rd party libs disclaimer

* Put third-party stuff into a separate folder

* Separate third-party stuff in ToC too

* Update links

* Move stuff that is not really (only) a client library into a separate page

* Add clickhouse-hdfs-loader link

* Some introduction for "interfaces" section

* Rewrite tcp.md

* http_interface.md -> http.md

* fix link

* Remove unconvenient error for now

* try to guess anchor instead of failing

* remove symlink

* Remove outdated info from introduction

* remove ru roadmap.md

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* Update roadmap.md

* lost file

* Title case in toc_en.yml

* Sync "Functions" ToC section with en

* Remove reference to pretty old ClickHouse release from docs

* couple lost symlinks in fa

* Close quote in proper place

* Rewrite en/getting_started/index.md

* Sync en<>ru getting_started/index.md

* minor changes

* Some gui.md refactoring

* Translate DataGrip section to ru

* Translate DataGrip section to zh

* Translate DataGrip section to fa

* Translate DBeaver section to fa

* Translate DBeaver section to zh

* Split third-party GUI to open-source and commercial

* Mention some RDBMS integrations + ad-hoc translation fixes

* Add rel="external nofollow" to outgoing links from docs

* Lost blank lines

* Fix class name

* More rel="external nofollow"

* Apply suggestions by @sundy-li

* Mobile version of front page improvements

* test

* test 2

* test 3

* Update LICENSE

* minor docs fix

* Highlight current article as suggested by @sundy-li

* fix link destination

* Introduce backup.md (only "en" for now)

* Mention INSERT+SELECT in backup.md

* Some improvements for replication.md

* Add backup.md to toc

* Mention clickhouse-backup tool

* Mention LightHouse in third-party GUI list

* Introduce interfaces/third-party/proxy.md

* Add clickhouse-bulk to proxy.md

* Major extension of integrations.md contents

* fix link target

* remove unneeded file

* better toc item name

* fix markdown

* better ru punctuation

* Add yet another possible backup approach

* Simplify copying permalinks to headers

* Support non-eng link anchors in docs + update some deps

* Generate anchors for single-page mode automatically

* Remove anchors to top of pages

* Remove anchors that nobody links to

* build fixes

* fix few links

* restore css

* fix some links

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* more docs fixes

* docs fixes

* NULL anchor

* update urllib3 dependency

* more fixes
2018-12-12 20:28:00 +03:00

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# Dictionary
Движок `Dictionary` отображает данные [словаря](../../query_language/dicts/external_dicts.md) как таблицу ClickHouse.
Рассмотрим для примера словарь `products` со следующей конфигурацией:
```xml
<dictionaries>
<dictionary>
<name>products</name>
<source>
<odbc>
<table>products</table>
<connection_string>DSN=some-db-server</connection_string>
</odbc>
</source>
<lifetime>
<min>300</min>
<max>360</max>
</lifetime>
<layout>
<flat/>
</layout>
<structure>
<id>
<name>product_id</name>
</id>
<attribute>
<name>title</name>
<type>String</type>
<null_value></null_value>
</attribute>
</structure>
</dictionary>
</dictionaries>
```
Запрос данных словаря:
``` sql
select name, type, key, attribute.names, attribute.types, bytes_allocated, element_count,source from system.dictionaries where name = 'products';
SELECT
name,
type,
key,
attribute.names,
attribute.types,
bytes_allocated,
element_count,
source
FROM system.dictionaries
WHERE name = 'products'
```
```
┌─name─────┬─type─┬─key────┬─attribute.names─┬─attribute.types─┬─bytes_allocated─┬─element_count─┬─source──────────┐
│ products │ Flat │ UInt64 │ ['title'] │ ['String'] │ 23065376 │ 175032 │ ODBC: .products │
└──────────┴──────┴────────┴─────────────────┴─────────────────┴─────────────────┴───────────────┴─────────────────┘
```
В таком виде данные из словаря можно получить при помощи функций [dictGet*](../../query_language/functions/ext_dict_functions.md#ext_dict_functions).
Такое представление неудобно, когда нам необходимо получить данные в чистом виде, а также при выполнении операции `JOIN`. Для этих случаев можно использовать движок `Dictionary`, который отобразит данные словаря в таблицу.
Синтаксис:
```
CREATE TABLE %table_name% (%fields%) engine = Dictionary(%dictionary_name%)`
```
Пример использования:
``` sql
create table products (product_id UInt64, title String) Engine = Dictionary(products);
CREATE TABLE products
(
product_id UInt64,
title String,
)
ENGINE = Dictionary(products)
```
```
Ok.
0 rows in set. Elapsed: 0.004 sec.
```
Проверим что у нас в таблице?
``` sql
select * from products limit 1;
SELECT *
FROM products
LIMIT 1
```
```
┌────product_id─┬─title───────────┐
│ 152689 │ Some item │
└───────────────┴─────────────────┘
1 rows in set. Elapsed: 0.006 sec.
```
[Оригинальная статья](https://clickhouse.yandex/docs/ru/operations/table_engines/dictionary/) <!--hide-->