mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-11-27 10:02:01 +00:00
59 lines
2.1 KiB
Markdown
59 lines
2.1 KiB
Markdown
---
|
|
toc_folder_title: Settings
|
|
toc_priority: 55
|
|
toc_title: Introduction
|
|
---
|
|
|
|
# Settings {#session-settings-intro}
|
|
|
|
There are multiple ways to make all the settings described in this section of documentation.
|
|
|
|
Settings are configured in layers, so each subsequent layer redefines the previous settings.
|
|
|
|
Ways to configure settings, in order of priority:
|
|
|
|
- Settings in the `users.xml` server configuration file.
|
|
|
|
Set in the element `<profiles>`.
|
|
|
|
- Session settings.
|
|
|
|
Send `SET setting=value` from the ClickHouse console client in interactive mode.
|
|
Similarly, you can use ClickHouse sessions in the HTTP protocol. To do this, you need to specify the `session_id` HTTP parameter.
|
|
|
|
- Query settings.
|
|
|
|
- When starting the ClickHouse console client in non-interactive mode, set the startup parameter `--setting=value`.
|
|
- When using the HTTP API, pass CGI parameters (`URL?setting_1=value&setting_2=value...`).
|
|
- Make settings in the [SETTINGS](../../sql-reference/statements/select/index.md#settings-in-select) clause of the SELECT query. The setting value is applied only to that query and is reset to default or previous value after the query is executed.
|
|
|
|
Settings that can only be made in the server config file are not covered in this section.
|
|
|
|
## Custom Settings {#custom_settings}
|
|
|
|
In addition to the common [settings](../../operations/settings/settings.md), users can define custom settings.
|
|
|
|
A custom setting name must begin with one of predefined prefixes. The list of these prefixes must be declared in the [custom_settings_prefixes](../../operations/server-configuration-parameters/settings.md#custom_settings_prefixes) parameter in the server configuration file.
|
|
|
|
```xml
|
|
<custom_settings_prefixes>custom_</custom_settings_prefixes>
|
|
```
|
|
|
|
To define a custom setting use `SET` command:
|
|
|
|
```sql
|
|
SET custom_a = 123;
|
|
```
|
|
|
|
To get the current value of a custom setting use `getSetting()` function:
|
|
|
|
```sql
|
|
SELECT getSetting('custom_a');
|
|
```
|
|
|
|
**See Also**
|
|
|
|
- [Server Configuration Settings](../../operations/server-configuration-parameters/settings.md)
|
|
|
|
[Original article](https://clickhouse.tech/docs/en/operations/settings/) <!--hide-->
|