Changes the value and/or level of a system setting. To show all the current settings, use SHOW SETTINGS.
Set 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.
The SETVAR is an optimizer hint that can be specified within a single SQL statement to provide finer control over statement execution plans. This allows you to configure settings temporarily (only for the duration of the SQL statement) with a Key=Value pair. For the available settings you can configure with the SETVAR, see SHOW SETTINGS.