ClickHouse/docs/zh/operations/settings/constraints-on-settings.md
Ivan Blinkov cd14f9ebcb
SQL reference refactoring (#10857)
* split up select.md

* array-join.md basic refactoring

* distinct.md basic refactoring

* format.md basic refactoring

* from.md basic refactoring

* group-by.md basic refactoring

* having.md basic refactoring

* additional index.md refactoring

* into-outfile.md basic refactoring

* join.md basic refactoring

* limit.md basic refactoring

* limit-by.md basic refactoring

* order-by.md basic refactoring

* prewhere.md basic refactoring

* adjust operators/index.md links

* adjust sample.md links

* adjust more links

* adjust operatots links

* fix some links

* adjust aggregate function article titles

* basic refactor of remaining select clauses

* absolute paths in make_links.sh

* run make_links.sh

* remove old select.md locations

* translate docs/es

* translate docs/fr

* translate docs/fa

* remove old operators.md location

* change operators.md links

* adjust links in docs/es

* adjust links in docs/es

* minor texts adjustments

* wip

* update machine translations to use new links

* fix changelog

* es build fixes

* get rid of some select.md links

* temporary adjust ru links

* temporary adjust more ru links

* improve curly brace handling

* adjust ru as well

* fa build fix

* ru link fixes

* zh link fixes

* temporary disable part of anchor checks
2020-05-15 07:34:54 +03:00

76 lines
2.3 KiB
Markdown

---
machine_translated: true
machine_translated_rev: 72537a2d527c63c07aa5d2361a8829f3895cf2bd
toc_priority: 62
toc_title: "\u5BF9\u8BBE\u7F6E\u7684\u9650\u5236"
---
# 对设置的限制 {#constraints-on-settings}
在设置的约束可以在定义 `profiles` 一节 `user.xml` 配置文件,并禁止用户更改一些设置与 `SET` 查询。
约束定义如下:
``` xml
<profiles>
<user_name>
<constraints>
<setting_name_1>
<min>lower_boundary</min>
</setting_name_1>
<setting_name_2>
<max>upper_boundary</max>
</setting_name_2>
<setting_name_3>
<min>lower_boundary</min>
<max>upper_boundary</max>
</setting_name_3>
<setting_name_4>
<readonly/>
</setting_name_4>
</constraints>
</user_name>
</profiles>
```
如果用户试图违反约束,将引发异常,并且设置不会更改。
支持三种类型的约束: `min`, `max`, `readonly`. 该 `min` 和 `max` 约束指定数值设置的上边界和下边界,并且可以组合使用。 该 `readonly` constraint指定用户根本无法更改相应的设置。
**示例:** 让 `users.xml` 包括行:
``` xml
<profiles>
<default>
<max_memory_usage>10000000000</max_memory_usage>
<force_index_by_date>0</force_index_by_date>
...
<constraints>
<max_memory_usage>
<min>5000000000</min>
<max>20000000000</max>
</max_memory_usage>
<force_index_by_date>
<readonly/>
</force_index_by_date>
</constraints>
</default>
</profiles>
```
以下查询都会引发异常:
``` sql
SET max_memory_usage=20000000001;
SET max_memory_usage=4999999999;
SET force_index_by_date=1;
```
``` text
Code: 452, e.displayText() = DB::Exception: Setting max_memory_usage should not be greater than 20000000000.
Code: 452, e.displayText() = DB::Exception: Setting max_memory_usage should not be less than 5000000000.
Code: 452, e.displayText() = DB::Exception: Setting force_index_by_date should not be changed.
```
**注:**`default` 配置文件具有特殊的处理:所有定义的约束 `default` 配置文件成为默认约束,因此它们限制所有用户,直到为这些用户显式复盖它们。
[原始文章](https://clickhouse.tech/docs/en/operations/settings/constraints_on_settings/) <!--hide-->