mssql 优化之IO部分

1. Consider a table with two non-clustered indexes that could satisfy a SELECT query.The first index has all the required columns.The second index has all the required columns, plus several additional columns.
2. SQL 服务器：最大限度的减少磁盘 I/O。  URL：http://technet.microsoft.com/zh-cn/magazine/jj643251.aspx