MySQL Query: 
                SELECT 
                    SQL_CALC_FOUND_ROWS o.*,  
                    IF(currency_id=1,(price*1.76),
                        IF(currency_id=2,(price*1.95583),
                            IF(currency_id=3,(price*2.3),price)) ) AS sort_price 
                FROM `obiavi` o
                WHERE 1  AND is_validate > 0  AND is_expired = 0 
                GROUP by o.id
                
                ORDER by is_vip DESC, o.id DESC
                LIMIT 21820, 20<br />MySQL Error: Out of sort memory, consider increasing server sort buffer size<br />