Syntax

mysql> select topn_array(k3,3) from baseall;
| topn_array(`k3`, 3)      |
+--------------------------+
+--------------------------+
1 row in set (0.02 sec)
mysql> select topn_array(k3,3,100) from baseall;
| topn_array(`k3`, 3, 100) |
+--------------------------+
| [3021, 2147483647, 5014] |