使用ViewFields提升SPQuery查询性能

        用SPquery查询文档库文件，当使用了Scope=\"Recursive\后，性能大幅下降，通过开发人员面板看到我的webpart查询数据耗时：EnsureListItemsData (196.45 ms)

       在查询语句中加入ViewFields限制，只取需要用到的字段，查询时间能缩短将近一半：EnsureListItemsData (96.47 ms)

   1: sPQuery.ViewFields = string.Concat(

   2:                    "<FieldRef Name='FileLeafRef' />",

   3:                    "<FieldRef Name='EncodedAbsUrl' />",

   4:                    "<FieldRef Name='Modified' />",

   5:                    "<FieldRef Name='File_x0020_Type' />",

   6:                    "<FieldRef Name='LinkTitle' />",

   7:                    "<FieldRef Name='ServerUrl' />",

   8:                    "<FieldRef Name='PermMask' />");                

   9: sPQuery.ViewFieldsOnly = true;