内容摘要：在本文里，我会通过比较XML AUTO功能和标准的T-SQL命令来显示性能上的差异。在我的测试过程中，我会仅仅涉及到XML AUTO功能的一个比较小的基础的部分，同时我也建议大家在你自己的环境当中来测试你将要使用的XML功能。
这看起来显示了T-SQL查询比其他的方式表现的要好。XML AUTO的XML查询使用了超过八倍的CPU资源但却产生了一样的I/O。复杂的XML命令比T-SQL命令消耗了超过80倍的读取操作，同时还有许多写操作和上面的六倍的CPU。
什么时候分析命令产生的I/O统计数据：
Table'Employes'.Scancount1,logicalreads8247,physical
reads0,read-aheadreads7520,loblogicalreads0,lob
physicalreads0,lobread-aheadreads0.
Table'Employes'.Scancount1,logicalreads8247,physical
reads0,read-aheadreads4221,loblogicalreads0,lob
physicalreads0,lobread-aheadreads0.
Table'Employes'.Scancount1,logicalreads8247,physical
reads500,read-aheadreads2586,loblogicalreads0,lob
physicalreads0,lobread-aheadreads0.
Table'Worktable'.Scancount0,logicalreads7,physical
reads1,read-aheadreads0,loblogicalreads229128,lob
physicalreads285,lobread-aheadreads43082.
Table'Employes'.Scancount1,logicalreads8247,physical
reads0,read-aheadreads1394,loblogicalreads0,lob
physicalreads0,lobread-aheadreads0.
Table'Worktable'.Scancount0,logicalreads7,physical
reads0,read-aheadreads0,loblogicalreads230170,lob
physicalreads0,lobread-aheadreads43115.
Table'Employes'.Scancount1,logicalreads8247,physical
reads125,read-aheadreads3835,loblogicalreads0,lob
physicalreads0,lobread-aheadreads0.
Table'Worktable'.Scancount0,logicalreads7,physical
reads0,read-aheadreads0,loblogicalreads230170,lob
physicalreads140,lobread-aheadreads43115.
来源：TechTarget 作者：Michelle Gutzait 责编：豆豆技术应用
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