如何提高mysql update性能

[SuperCustomer]

如何提高这条语句的性能

UPDATE FactLogin_201305 a,
 Leads_2012 b
SET a.theCount = b.factCount,
 a.theRoi = b.roi > 0
WHERE
	a.allotStep = b.allotStep
AND a.salesType = b.salesType
AND a.cityOrder = b.cityOrder
AND a.salary = b.salary
AND a.gender = b.gender
AND a.education = b.education
AND a.ageStep = b.ageStep
AND a.gzt10 = b.gzt10;

[ACMAIN_CHM]

create index xxx on 记录多的表 (allotStep,salesType,cityOrder,salary,gender,education,ageStep,gzt10);

[WWWWA]

在两表的连接字段上建立索引 即WHERE　中的字段 allotStep,salesType,cityOrder,salary,gender,education,ageStep,gzt10

[Rotel-刘志东]

在where 字段创建索引allotStep,salesType,cityOrder,salary,gender,education,ageStep,gzt10

[rucypli]

SET a.theCount = b.factCount, a.theRoi = b.roi > 0 这是什么意思