I have relatively big system with 2 000 users , 10 TB archive. After update to 4.9.2 ( from 4.9.1 ) system isn´t stable as it was and we got situation, that archive times was 10 time longer and some jobs stalled. Aborting job did nothing , killing job on Worker did nothing too, stopping Retain server a MariaDB server created rollback operation for several hours. Currently there is rollback of 1,3 millions rows.
I´m curious what is cause of so many rows in rollback.
David