mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-05 14:02:21 +00:00
74 lines
2.4 KiB
Markdown
74 lines
2.4 KiB
Markdown
---
|
||
sidebar_position: 62
|
||
sidebar_label: Constraints on Settings
|
||
---
|
||
|
||
# Constraints on Settings
|
||
|
||
The constraints on settings can be defined in the `profiles` section of the `user.xml` configuration file and prohibit users from changing some of the settings with the `SET` query.
|
||
The constraints are defined as the following:
|
||
|
||
``` 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>
|
||
```
|
||
|
||
If the user tries to violate the constraints an exception is thrown and the setting isn’t changed.
|
||
There are supported three types of constraints: `min`, `max`, `readonly`. The `min` and `max` constraints specify upper and lower boundaries for a numeric setting and can be used in combination. The `readonly` constraint specifies that the user cannot change the corresponding setting at all.
|
||
|
||
**Example:** Let `users.xml` includes lines:
|
||
|
||
``` 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>
|
||
```
|
||
|
||
The following queries all throw exceptions:
|
||
|
||
``` 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.
|
||
```
|
||
|
||
**Note:** the `default` profile has special handling: all the constraints defined for the `default` profile become the default constraints, so they restrict all the users until they’re overridden explicitly for these users.
|
||
|
||
[Original article](https://clickhouse.com/docs/en/operations/settings/constraints_on_settings/) <!--hide-->
|