Trying to execute json_extract extension brings up an error:
mysql:research@analytics-store.eqiad.wmnet [log]> select json_extract(userAgent, '$device_family') from NavigationTiming_15485142 order by timestamp desc limit 5;
ERROR 1370 (42000): execute command denied to user 'research'@'%' for routine 'log.json_extract'
Not sure if that means extension is not installed, if so, could it be?