Cannot execute query [SELECT o.id AS id, o.tiposcheda AS type, o.titolo AS title, o.titoloperord AS ordered_title, p.intestazione AS author FROM opera o JOIN multi_rel m ON m.tipoa = 'opera' AND m.ida = o.id LEFT JOIN persona p ON o.autore = p.id WHERE m.idb = '5535' AND m.tipob = 'bibliografia' UNION SELECT o.id AS id, o.tiposcheda AS type, o.titolo AS title, o.titoloperord AS ordered_title, p.intestazione AS author FROM opera o JOIN rel r ON r.tipoa = 'opera' AND r.ida = o.id LEFT JOIN persona p ON o.autore = p.id WHERE r.idb = '5535' AND r.tipob = 'bibliografia' ORDER BY author, ordered_title]: Got error 28 from storage engine