_NOT_QUERY: Can't create/write to file '/tmp/#sql_5f7_1.MYI' (Errcode: 30)

Query: SELECT c.*, DATE_FORMAT(c.created, '%d %m %y') as created_name, cc.name as category_name, cc.name_2 as category_name_2, cc.name_3 as category_name_3, cc.name_4 as category_name_4, cc.name_5 as category_name_5 FROM reg_content as c, reg_content_category as cc, reg_content_value as cv WHERE cc.id=cv.id_category AND cv.id_category='210401' AND c.published='1' AND c.id=cv.id_content ORDER BY c.rating DESC, c.id DESC, c.name ASC