'db'=>array(
...
'initSQLs' => array(
'set global max_allowed_packet = 1500000', // 1500000 - your value (if you have permissions to change this value - it helps)
),
),
Thanks. The newest stable release (released today) does know this parameter. (However, I don’t need it any more. In the meantime, I found out that the oversized data came from wrong export data. An image (included in XML) was of the wrong format.)