Failed to execute the SQL query

 select i.title, i.id,  UNIX_TIMESTAMP( ifnull(i.pubdate, i.added)) as ts_,  year( ifnull(i.pubdate, i.added)) as y_,  month( ifnull(i.pubdate, i.added)) as m_,  dayofmonth( ifnull(i.pubdate, i.added)) as d_  from  news_item  i  where i.cid = 4   and not(i.unread & 4)  order by ts_ desc, i.id asc

Error 1: Can't create/write to file '/tmp/MYoHQfJu' (Errcode: 5)