UNSET

Sets one or more system settings back to their default values. The settings will also be reset to the initial SESSION level if they were set to GLOBAL level. See Examples for how to reset a GLOBAL setting with UNSET. For more information about the setting levels, see Managing Settings. To show all the current settings, use SHOW SETTINGS.

See also: SET

Syntax

UNSET <setting_name> | ( <setting_name> [, <setting_name> ...])

Examples

This example assigns new values to some system settings, changes their levels to GLOBAL, then resets them to their defaults:

---Show default values
SELECT name, value, default, level from system.settings where name in ('sql_dialect', 'timezone');

| name                          | value      | default    | level   |
|-------------------------------|------------|------------|---------|
| sql_dialect                   | PostgreSQL | PostgreSQL | SESSION |
| timezone                      | UTC        | UTC        | SESSION |

---Set new values
SET GLOBAL sql_dialect='MySQL';
SET GLOBAL timezone='Asia/Shanghai';

SELECT name, value, default, level from system.settings where name in ('sql_dialect', 'timezone');

| name                          | value         | default    | level  |
|-------------------------------|---------------|------------|--------|
| sql_dialect                   | MySQL         | PostgreSQL | GLOBAL |
| timezone                      | Asia/Shanghai | UTC        | GLOBAL |

---Reset to default values
UNSET (timezone, sql_dialect);

SELECT name, value, default, level from system.settings where name in ('sql_dialect', 'timezone');

| name                          | value      | default    | level   |
|-------------------------------|------------|------------|---------|
| sql_dialect                   | PostgreSQL | PostgreSQL | SESSION |
| timezone                      | UTC        | UTC        | SESSION |