SQL Server CE性能，从表中选择需要8s的7000条记录

Question

我有SQL Server CE 3.5数据库。我运行以下代码：

private void Load(string sql) 
{ 
    if (connection.State != ConnectionState.Open) 
    connection.Open(); 
    SqlCeDataAdapter sqlCeDataAdapter = new SqlCeDataAdapter(sql, connection); 

    Stopwatch watch = new Stopwatch(); 

    DataSet dataSet = new DataSet(); 
    try 
    { 
    Cursor.Current = Cursors.WaitCursor; 
    watch.Start(); 

    sqlCeDataAdapter.Fill(dataSet, "items"); 
    sqlCeDataAdapter.Dispose(); 

    var myBind = new BindingSource(dataSet, "items"); 
    grid.DataSource = myBind; 
    } 
    finally 
    { 
    watch.Stop(); 
    Cursor.Current = Cursors.Default; 
    MessageBox.Show(watch.ElapsedMilliseconds.ToString()); 
    }  
} 

Load ("select a1, a2 from table"); 

SQL Server CE或者它应该更快加载吗？

我该怎么做才能让这个选择更快？

当我使用与其它表连接，时间显着长大......

编辑：

我改变了以下新版本的代码，但还是7.5秒。 ...

private void Load2 (string sql) 
{ 
    if (connection.State != System.Data.ConnectionState.Open) 
    { 
    connection.Open(); 
    } 

    using (SqlCeCommand command = new SqlCeCommand(sql, connection)) 
    { 
    Stopwatch watch = new Stopwatch(); 

    Cursor.Current = Cursors.WaitCursor; 
    watch.Start(); 
    using (SqlCeDataReader reader = command.ExecuteReader()) 
    { 
     DataSet dataSet = new DataSet(); 

     dataSet.Tables.Add("items"); 

     dataSet.Tables["items"].Columns.Add("s1"); 
     dataSet.Tables["items"].Columns.Add("s2"); 

     while (reader.Read()) 
     { 
     string s1 = reader.GetString(0); 
     string s2 = reader.GetString(1); 

     dataSet.Tables["items"].Rows.Add(s1, s2); 
     } 
     watch.Stop(); 
     Cursor.Current = Cursors.Default; 
     MessageBox.Show(watch.ElapsedMilliseconds.ToString()); 

     BindingSource binding = new BindingSource(dataSet, "items"); 
     grid.DataSource = binding; 
    } 
    } 
} 

Answer 1

SqlCeDataAdapter.Fill(...)只是出了名的慢。如果您确实需要这种性能，您需要使用SqlCeDataReader来代替。

private void Load(string sql) { 
    if (connection.State != System.Data.ConnectionState.Open) { 
     connection.Open(); 
    } 

    using (SqlCeCommand command = new SqlCeCommand(sql, connection)) { 
     using (SqlCeDataReader reader = command.ExecuteReader()) { 
      DataSet dataSet = new DataSet(); 

      dataSet.Tables.Add("items"); 

      while (reader.Read()) { 
       DataRow row = dataSet.Tables["items"].NewRow(); 
       // fill your row 

       dataSet.Tables["items"].Rows.Add(row); 
      } 

      BindingSource binding = new BindingSource(dataSet, "items"); 
      grid.DataSource = binding; 
     } 
    } 
} 

当然，添加你的错误处理，并根据你的喜好进行清理。还有Entity Framework，与DbDataAdapter实施相比，它的性能不错。

由于您使用的是SqlCe，因此您还有其他限制因素，例如磁盘IO，并且您没有服务器通过任何优化处理SQL事务。