Tom Barrett

It also seems like it's the combination of GROUP BY person_group.id ORDER BY person_group.`name` which is triggering the temporary table/filesort. https://stackoverflow.com/questions/13633406/using-index-using-temporary-using-filesort-how-to-fix-this Removing the ORDER BY takes away the temp-table/filesort from...

Moving the member-counting into a subquery, so the outer query doesn't need a GROUP BY, didn't help as much as I'd hoped. MariaDB probably the best solution. Also, the member-count...