MySQL_class: Database Error occured!

 CODE: 1021
 DESC: Disk full (/tmp/#sql_7a08_2.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
 FILE: index.php
QUERY: select customer.*,cust_cat.cust_id,cust_cat.cat_id,link_counter.counter from customer left join cust_cat on cust_cat.cust_id=customer.id left join link_counter on link_counter.link_id=customer.id and link_counter.type='client' where cust_cat.cat_id='525' and customer.status='Y' and customer.deleted='N' and customer.seller='Y' Order by customer.paid,link_counter.counter desc limit 0,15
 QCNT: 6
 INFO: QueryResult('select customer.*,cust_cat.cust_id,cust_cat.cat_id,link_counter.counter from customer left join cust_cat on cust_cat.cust_id=customer.id left join link_counter on link_counter.link_id=customer.id and link_counter.type='client' where cust_cat.cat_id='525' and customer.status='Y' and customer.deleted='N' and customer.seller='Y' Order by customer.paid,link_counter.counter desc limit 0,15') failed!

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PHP v5.6.40 / MySQL Class v0.36