Discuz! Database Error

(1) Can't create/write to file '/tmp/#sql_81c_3.MYI' (Errcode: 28 - No space left on device)

SELECT t.*,p.message,p.pid,f.name FROM forum_thread t LEFT JOIN forum_post p on p.tid=t.tid LEFT JOIN forum_forum f on f.fid=t.fid WHERE t.displayorder>=0 and p.first=1 and t.fid='40' group by t.tid ORDER BY t.displayorder DESC,t.`dateline` DESC LIMIT 1380 , 20

PHP Debug

No.	File	Line	Code
1	portal.php	32	require_once(%s)
2	source/module/portal/portal_index.php	32	include_once(%s)
3	data/template/3_diy_portal_index.tpl.php	80	require_once(%s)
4	template/quater_10_csdn/php/thread_list1.php	24	discuz_database::query(%s)
5	source/class/discuz/discuz_database.php	142	db_driver_mysqli->query(%s, false, false)
6	source/class/db/db_driver_mysqli.php	148	db_driver_mysqli->halt(%s, %d, %s)
7	source/class/db/db_driver_mysqli.php	223	break()