UNSET

Sets one or more 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.

See also: SET

Syntax

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

Examples

This example assigns new values to some 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', 'wait_for_async_insert_timeout');

| name                          | value      | default    | level   |
|-------------------------------|------------|------------|---------|
| sql_dialect                   | PostgreSQL | PostgreSQL | SESSION |
| timezone                      | UTC        | UTC        | SESSION |
| wait_for_async_insert_timeout | 100        | 100        | SESSION |

---Set new values
SET GLOBAL sql_dialect='MySQL';
SET GLOBAL timezone='Asia/Shanghai';
SET GLOBAL wait_for_async_insert_timeout=20000;

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

| name                          | value         | default    | level  |
|-------------------------------|---------------|------------|--------|
| sql_dialect                   | MySQL         | PostgreSQL | GLOBAL |
| timezone                      | Asia/Shanghai | UTC        | GLOBAL |
| wait_for_async_insert_timeout | 20000         | 100        | GLOBAL |

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

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

| name                          | value      | default    | level   |
|-------------------------------|------------|------------|---------|
| sql_dialect                   | PostgreSQL | PostgreSQL | SESSION |
| timezone                      | UTC        | UTC        | SESSION |
| wait_for_async_insert_timeout | 100        | 100        | SESSION |