I've been doing some testing with various versions of MySQL and MariaDB regarding slow log rotation. And it looks like MariaDB (tested 10.4, 10.5, 10.6 so far) suffers from a bug. Setup: sloq_query_log=1 long_query_time=0 # sysbench oltp_read_write --threads=$(nproc) Action: mv slow.log slow.log.1 MariaDB [(none)]> flush slow logs; ^^ This never returns (never as in I haven't tried waiting for > 10 minutes). On MySQL 5.5 this is instantaneous. On 5.6 - 8.0 it takes a few seconds, worst case I measured over the weekend is 77s, which is pretty terrible, but with MariaDB 10.3 - 10.6 it never seems to complete at all. If I kill sysbench, it completes immediately. On 10.3 it works, in line with MySQL 5.6 - 8.0. This seems like a rather significant bug.