优化EF的性能

Entity Framework的性能优化：

1.使用MergeOption.NoTracking

（发现添加这个代码后，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）

  在EF生成的ObjectContext的构造里设置MergeOption， 如：

    public partial class protocoldbEntities : ObjectContext
    {
        #region Constructors
    
        /// <summary>
        /// Initializes a new protocoldbEntities object using the connection string found in the 'protocoldbEntities' section of the application configuration file.
        /// </summary>
        public protocoldbEntities() : base("name=protocoldbEntities", "protocoldbEntities")
        {
            this.protocolnodes.MergeOption = MergeOption.NoTracking;
            this.protocolversionhistories.MergeOption = MergeOption.NoTracking;
 
            this.ContextOptions.LazyLoadingEnabled = true;
            OnContextCreated();
        }

2.    使用IQueryable和Compiled Queries
     如： 定义一个Func变量，   CompiledQuery.Compile中传入entity对象，查询结果，以及可选的查询条件 。此例中，protocolDB是entity， 包含protocolnodes表， 
                    //                
                    private static Func<protocoldbEntities, string, protocolnode> _protocolNodeByUIDQueryFunc;
  
                    //
             if (null == _protocolNodeByUIDQueryFunc)
                    {
                        _protocolNodeByUIDQueryFunc = CompiledQuery.Compile<protocoldbEntities, string, protocolnode>((ctx, uid) =>
                            ctx.protocolnodes.FirstOrDefault(p => p.ProtocolNodeUID == uid)
                            );
                    }
 
                    protocolnode temp = _protocolNodeByUIDQueryFunc.Invoke(protocolDB, UID);
                    protocolDB.Refresh(RefreshMode.StoreWins, temp);//必须调用， 这样查询的数据才是数据库最新的，不然会出现数据库获取的数据是旧的。
3.     创建视图
http://blogs.msdn.com/b/adonet/archive/2008/06/20/how-to-use-a-t4-template-for-view-generation.aspx

http://www.asp.net/web-forms/tutorials/continuing-with-ef/maximizing-performance-with-the-entity-framework-in-an-asp-net-web-application