求一个SQL语句的优化

[lifeixie]

select a.id,a.cretime,c.src,c.dst,a.args from voicefiles a join callsession_acts b on a.associate = b.callsessionid and b.var1value = a.filename and folder = '1' and a.cretime >= '2010-5-31 2:00:00' and a.cretime < '2010-5-31 4:00:00' join cdr c on c.userfield = CONCAT(b.callsessionid,',',b.cdruniqueid) and c.src = '8005' and c.dst = '67101' and disposition = 'ANSWERED' limit 60



voicefiles 表
associate，filename，folder 等

callsession_acts 表
callsessionid，var1value 等

voicefiles的 associate，与 callsession_acts.callsessionid 关联,filename 和 var1value 关联，其中
callsession_acts表中 var1value不重复的（加callsessionid 有别的用 ）

cdr
userfield，disposition 等

其中 userfield = callsessionid，b.cdruniqueid
比如
userfied = 111,222
那 callsessionid = 111
cdruniqueid = 222
都字符



请问 此SQL语句如何优化 才能是性能更加，减少服务器负担，一条语句

[lifeixie]

表不是我设计的，有历史原因没办法

[ACMAIN_CHM]

explain select a.id,a.cretime,c.src,c.dst,a.args from voicefiles a join callsession_acts b on a.associate = b.callsessionid and b.var1value = a.filename and folder = '1' and a.cretime >= '2010-5-31 2:00:00' and a.cretime < '2010-5-31 4:00:00' join cdr c on c.userfield = CONCAT(b.callsessionid,',',b.cdruniqueid) and c.src = '8005' and c.dst = '67101' and disposition = 'ANSWERED' limit 60;

show index from voicefiles;
show index from callsession_acts;
show index from cdr;

贴切出来看一下。

[lifeixie]

http://item.taobao.com/auction/item_detail.htm?item_num_id=4690350008

图在这里，这上面的图，没相册，没法弄图

[动感星空]

这种问题我也经常会遇到，可惜能力有限，望楼主找到高人，帮顶！

[lifeixie]

顶一下！！！！！！！！！！！！！

[WWWWA]

连接字段上建立过索引没有

[ACMAIN_CHM]

[Quote]图在这里，这上面的图，没相册，没法弄图[/Quote]
直接贴你的文本。