update statistics伪造统计信息

 当我们想要分析某些语句在一定数据量后的执行计划情况是可能会进行数据的模拟，伪造大量的数据。但其实这个工作挺费劲了，经朋友介绍在网上看到下面这种伪造统计信息的方式，对于如果只是分析执行计划的情况很方便。

use tempdb

go

create table t1(i int, j int)

go

create table t2(h int, k int)

go

set statistics profile on

go

select distinct(i) from t1

go

select * from t1, t2 where i = k order by j + k

go

update statistics t1 with rowcount = 10000, pagecount = 10000

update statistics t2 with rowcount = 100000, pagecount = 100000

go

select distinct(i) from t1 option (recompile)

go

select * from t1, t2 where i = k order by j + k option (recompile)

如果select中没有增加recomplite需要进行cache的清除：dbcc freeproccache

转自：http://blogs.msdn.com/b/queryoptteam/archive/2006/07/21/674350.aspx