The select query works as expected on 10.1.41-MariaDB-0+deb9u1 - Debian 9.9, but not on 10.3.21-MariaDB-1:10.3.21+maria~stretch-log - mariadb.org binary distribution .

Next Request indicates that there is 1 result

SELECT COUNT(*) FROM (SELECT *,UNIX_TIMESTAMP(time) as utcTime FROM `positions` `t` USE INDEX(dev_good_reason_time) WHERE ((`t`.`device_id`=54) AND (`t`.`log_reason`=0)) AND (`t`.`is_good_position`=1) GROUP BY `t`.`time` HAVING `t`.`time`=MAX(`t`.`time`)) sq;

Actual request returns no result on 10.3.21

SELECT *,UNIX_TIMESTAMP(time) as utcTime FROM `positions` `t` USE INDEX(dev_good_reason_time) WHERE ((`t`.`device_id`=54) AND (`t`.`log_reason`=0)) AND (`t`.`is_good_position`=1) GROUP BY `t`.`time` HAVING `t`.`time`=MAX(`t`.`time`) ORDER BY time DESC LIMIT 1;

The above query returns record number 30031 on mariadb 10.1.41

This was verified using the attached data imported in a new database after exporting the sample from the original database and anomyzing the data. The unexpected behavior occurs on the original database and both test databases running in the checked systems.

This is blocking (to use 10.3) - I downgraded the setup to 10.1 already used in production to be able to put this new instance in production. After downgrading to 10.1 the functionnality relying on this query works fine.