我有以下查询:如何优化此查询?
SELECT `masters_tp`.*, `masters_cp`.`cp` as cp, `masters_cp`.`punti` as punti
FROM (`masters_tp`)
LEFT JOIN `masters_cp` ON `masters_cp`.`nickname` = `masters_tp`.`nickname`
WHERE `masters_tp`.`stake` = 'report_A'
AND `masters_cp`.`stake` = 'report_A'
ORDER BY `masters_tp`.`tp` DESC, `masters_cp`.`punti` DESC
LIMIT 400;
有什么不对的查询可能影响服务器的内存?
这里是输出EXPLAIN
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+------------+------+---------------+------+---------+------+-------+----------------------------------------------+
| 1 | SIMPLE | masters_cp | ALL | NULL | NULL | NULL | NULL | 8943 | Using where; Using temporary; Using filesort |
| 1 | SIMPLE | masters_tp | ALL | NULL | NULL | NULL | NULL | 12693 | Using where |
我们不可能在没有更多信息的情况下回答这个问题。也许关于表格的一些信息以及它们中有多少数据? – scheibk 2009-08-14 10:56:54