https://drill.apache.org/docs/tutorial-develop-a-simple-function/
SELECT MASK(first_name, '*' , 3) FIRST , MASK(last_name, '#', 7) LAST FROM cp.`employee.json` LIMIT 5;
+----------+------------+
| FIRST | LAST |
+----------+------------+
| ***ri | ###### |
| ***rick | ####### |
| ***hael | ###### |
| ***a | #######ez |
| ***erta | ####### |
+----------+------------+
5 rows selected (2.259 seconds)