statistics io

statistic i/o是一个绘画选项，它返回与你运行的语句有关的i/o信息。为演示它的使用，先清空数据缓存

 dbcc dropcleanbuffers

然后运行下面的代码，开启该绘画选项并调用一个查询，

set statistics io on

select orderid,custid,empid,shipperid,orderdate,filter

from dbo.orders

where orderdate>='20060101'

  and orderdate<'20060201'

go

你应该得到下面类似的输出

table orders,scan count 1,logical reads 536,phycial reads 2, read-ahead reads 532,lob logical reads 0,lob physical reads 0,lob physical reads 0,lob read-ahead reads 0

输出表明了这个表在计划中被访问的次数(scan count);从缓存读取的页数(logical reads);从磁盘读取的页数(physical reads和read-ahead reads); 与大对象相关的逻辑读取数和物理读取数(lob logical reads ,lob physical reads,lob read-ahead reads)

 运行下面的代码关闭会话选项

set statistics io off