Question

Warning: mysql_query() [function.mysql-query]: 
MySQL server has gone away in filename.php on line 201

查询：

SELECT * FROM ta
    LEFT JOIN tb ON ta_id = tb_oid 
    LEFT JOIN tc ON ta_id = tc_oid 
    LEFT JOIN td ON ta_id = td_oid
WHERE 
    ta_time1 > 0 OR ta_time2 > 0 OR 
    tb_time1 > 0 OR tb_time2 > 0 OR 
    tc_time1 > 0 OR tc_time2 > 0 OR 
    td_time1 > 0 OR td_time2 > 0 
GROUP BY td_id 
ORDER BY  
    ta_time1 DESC, ta_time2 DESC,
    tb_time1 DESC, tb_time2 DESC,
    tc_time1 DESC, tc_time2 DESC,
    td_time1 DESC, td_time2 DESC
LIMIT 0, 40

如何优化此查询？

Answer 1

如果您还没有这样做，请在所有字段上设置索引。
尽可能使用小字段。例如。如果ID是128字节的字符串，你可以使用一个小的int，使用后者

顺便说一句，如果您不知道“已经消失”的含义，请查看手册： http://dev.mysql.com/doc/refman/5.0/en/gone-away.html

MySQL服务器已经消失了ERROR

1 个答案: