c# – 如何将DataReader映射到类属性并保持性能？

>所有数据连接字符串,
使用创建连接等
DbProviderFactories.
>代码混合了C#和VB.Net
多个图书馆.

我正在将DbDataReader映射到实体并具有一些基准：

[0] retrieved 159180 records in 45135 ms
[1] retrieved 159180 records in 45008 ms
[2] retrieved 159180 records in 44814 ms
[3] retrieved 159180 records in 44987 ms
[4] retrieved 159180 records in 44914 ms
[5] retrieved 159180 records in 45224 ms
[6] retrieved 159180 records in 45829 ms
[7] retrieved 159180 records in 60762 ms
[8] retrieved 159180 records in 52128 ms
[9] retrieved 159180 records in 47982 ms

考虑到从Sql Server Management Studio查询只需要17秒,这是一个非常大的时间和极差.我的选择声明：

“SELECT * FROM tbl_MyTable”

表包含43个字段,可能没有最佳索引;但是,执行全选,我不希望索引有问题.所以…这就是我在做的事情：

定义一个实体：

public class Concept
{
    #region Columns
    [DataParameter("ConceptID",DbType.Int32)]
    public Int32 ConceptID
    { get; set; }
    [DataParameter("ConceptName",DbType.String)]
    public string ConceptName
    { get; set; }
    [DataParameter("ConceptTypeID",DbType.Int32)]
    public Int32 ConceptTypeID
    { get; set; }
    [DataParameter("ActiveYN",DbType.Boolean)]
    public bool ActiveYN
    { get; set; }
    #endregion
}

查询DataReader：

for (int i = 0; i <= 99; i++)
{
    sw.Start();
    var results = session.QueryReader<Concept>(
        new SqlCommand(command),dr => new Concept());

    sw.Stop();

    Console.WriteLine("[{0}] retrieved {1} records in {2} ms",i,results.Count(),sw.ElapsedMilliseconds);
    sw.Reset();
}

……打电话：

Public Function QueryReader(Of TEntity As {Class,New})(ByVal Command As DbCommand,_
                                                        ByVal Projection As Func(Of DbDataReader,TEntity)) _
                                                        As IEnumerable(Of TEntity)

    Dim list As IEnumerable(Of TEntity)

    Command.Connection = dataReader.NewConnection
    Command.Connection.Open()

    Using _reader As DbDataReader = Command.ExecuteReader()
        list = _reader.Query(Of TEntity)(Projection).ToList()
    End Using

    Command.Connection.Close()

    Return list
End Function

…和扩展方法QueryReader< T>：编辑新TEntity()的位置 – 谢谢@Henk

public static IEnumerable<TEntity> Query<TEntity>(this DbDataReader Reader,Func<DbDataReader,TEntity> Projection)
    where TEntity : class,new()
{
    //   moving this reflection to another class
    Dictionary<string,PropertyInfo> props;

    while (Reader.Read())
    {
        TEntity entity = new TEntity();

        if (!entities.TryGetValue(typeof(TEntity).ToString(),out props))
        {
            //  reflection over TEntity
            props = (from p in entity.GetType().GetProperties()
                     from a in p.GetCustomAttributes(typeof(DataParameterAttribute),false)
                     select p)
                     .ToDictionary(p => p.Name);

            entities.Add(typeof(TEntity).ToString(),props);
        }

        foreach (KeyValuePair<string,PropertyInfo> field in props)
        {
            if (null != Reader[field.Key] && Reader[field.Key] != DBNull.Value)
            { field.Value.SetValue(entity,Reader[field.Key],null); }
        }

        yield return entity;
    }
}

任何有关提高性能的建议都将受到高度赞赏……

更新

我实现了@EtienneT建议的dapper-dot-net – 这里是检索时间：

[0] retrieved 159180 records in 6874 ms
[1] retrieved 159180 records in 6866 ms
[2] retrieved 159180 records in 6570 ms
[3] retrieved 159180 records in 6785 ms
[4] retrieved 159180 records in 6693 ms
[5] retrieved 159180 records in 6735 ms
[6] retrieved 159180 records in 6627 ms
[7] retrieved 159180 records in 6739 ms
[8] retrieved 159180 records in 6569 ms
[9] retrieved 159180 records in 6666 ms