Controls the formatting of unique identifier values when they are converted to strings.
When the uuid_has_hyphens option is set to On, the resulting strings contain four hyphens. For example, 12345678-1234-1234-1234-1234567890ab. With this option set to Off, the hyphens are omitted from the string. The database server supports UUID strings both with and without hyphens when converting a string to a unique identifier value.