"The object cannot be deleted because it was not found in the ObjectStateManager."

最近优化EF的性能时遇到一个问题， 当在EF生成的Entityes的构造里加上：

this.protocolnodes.MergeOption = MergeOption.NoTracking;this.protocolversionhistories.MergeOption = MergeOption.NoTracking;

 调用DeleteObject时，会导致"The object cannot be deleted because it was not found in the ObjectStateManager."错误。 

解决办法为， 先调用entity实例的Attach（deleteObj），参数为要删除的对象，然后调用ObjectStateManager.ChangeObjectState(deleteObj, EntityState.Deleted)，

具体参考
http://www.cnblogs.com/Benjamin/archive/2012/10/24/2736739.html