About upgrading procedures, there was no troubles. See “Updating to MariaDB 10.0.11” about HowTo.
I used this opportunity to replaced ‘MyISAM’ by ‘InnoDB’ about the wp_posts table’s ENGINE. As MariaDB5.5 didn’t support FULLTEXT indexes when I moved to it, I left the wp_posts table to ‘MyISAM’. It was for YARPP's performance. MariaDB 10.0.5 and later with ‘InnoDB’ support Fulltext Index. So, this replacement doesn’t seem to harm the plugin performance anymore.
Now I have no trouble with the upgrade, but I’ll carefully watch server logs for a while.