https://mariadb.com/kb/en/library/defragmenting-innodb-tablespaces/ seems to be silently broken in 10.2 or why is there a fat temp-file as well as the progress display from previous versions don't work in 10.1/10.2 in a useable way (a pseudo progress for small tables is nice but when you see no output at all when 'optimize table' is running on a table with 10 GB it's broken) "innodb-defragment = 1" is set -rw-rw---- 1 mysql mysql 2,6G 2017-09-30 21:39 '#sql-ib3030-2883732087.ibd' MariaDB [dbmail]> OPTIMIZE TABLE `dbmail_users`; +---------------------+----------+----------+-------------------------------------------------------------------+ | Table | Op | Msg_type | Msg_text | +---------------------+----------+----------+-------------------------------------------------------------------+ | dbmail.dbmail_users | optimize | note | Table does not support optimize, doing recreate + analyze instead | | dbmail.dbmail_users | optimize | status | OK | +---------------------+----------+----------+-------------------------------------------------------------------+