-- length should be 32 select length(hex(generateUUIDv4())); with generateUUIDv4() as uuid, replace(toString(uuid), '-', '') as str1, lower(hex(uuid)) as str2 select str1 = str2; -- hex on UUID always generate 32 characters even there're leading zeros select lower(hex(toUUID('00000000-80e7-46f8-0000-9d773a2fd319'))); -- length should be 128 select length(bin(generateUUIDv4())); -- bin on UUID always generate 128 characters even there're leading zeros select bin(toUUID('00000000-80e7-46f8-0000-9d773a2fd319'));