Error: MySQL: Disk full (/tmp/#sql-temptable-4ef-7d64ae-126a5.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")

Query: SELECT * FROM `object_documents` WHERE `item_main` = 1 ORDER BY RAND() LIMIT 1

File: /var/www/old_server/data/www/etl72.ru/includes/classes/mysql.class.php, Line 146