-- setting the SQL_SELECT_LIMIT will cause some queries get stuck (only a few, not all)

MariaDB [the_db]> set @@SQL_SELECT_LIMIT=2000;

Query OK, 0 rows affected (0.000 sec)

-- BUG!! then this query gets stuck forever, SQL_SELECT_LIMIT=2000 or 20000 or 200000 makes the same result.

MariaDB [the_db]> with t as ( select * from the_table where client_ip like '183.89.%' )  select count(*) from t group by username;

^C Ctrl-C -- query killed. Continuing normally.

ERROR 1317 (70100): Query execution was interrupted

-- however, the simple query runs without bug

MariaDB [the_db]> select * from the_table where client_ip like '183.89.%';

+----------+

...

+----------+

80 rows in set (0.035 sec)

-- then, reset the SQL_SELECT_LIMIT, everything works fine again.

MariaDB [the_db]> set @@SQL_SELECT_LIMIT=default;

Query OK, 0 rows affected (0.000 sec)

MariaDB [the_db]> with t as ( select * from the_table where client_ip like '183.89.%' )  select count(*) from t group by username;

+----------+

| count(*) |

+----------+

|        2 |

......

+----------+

17 rows in set (0.026 sec)