Question

我正在运行一个非常简单的select语句，它从一个大表（超过1000万行）返回一个varchar(50)列。该表已有pk

示例：

select employee_name from tblEmployees

在.net中，我使用SqlDataReader来回读数据

有时查询超时
SQL Server内存使用率上升，直到消耗所有服务器资源，并且在SqlDataReader和/或连接关闭时不会释放

请问有解决方法吗？

感谢。

代码：

    Dim M1 As String() = {"234701", "234703", "234704", "234705", "234706", "234707", "234708", "234709", "234802", "234803", "234804", "234805", "234806", "234807", "234808", "234809", "234810", "234811", "234812", "234813", "234814", "234815", "234816", "234817", "234818", "234819", "234909", "234902", "234903", "234905"}
    Dim M2 As String() = {"2347025", "2347026", "2347027", "2347028", "2347029"}
    Dim M3 As String() = {"23490", "23491"}

    Dim N1 As New Dictionary(Of Long, Byte) 'ok
    Dim N2 As New Dictionary(Of Long, Byte) 'maybe

    Function GetMobile(v As String) As Mobile
        If v.Length < 10 Then
            Return Nothing
        End If

        Dim sb = New Text.StringBuilder

        For i = 0 To v.Length - 1
            Select Case v(i)
                Case "0"c To "9"c
                    sb.Append(v(i))
            End Select
        Next

        Dim m = "234" + Right(sb.ToString, 10)

        If m.Length = 13 Then
            If M1.Contains(Left(m, 6)) OrElse M2.Contains(Left(m, 7)) Then
                Return New Mobile With {.number = CLng(m), .ok = OK.Yes}
            ElseIf Left(m, 6) = "234702" OrElse M3.Contains(Left(m, 5)) Then
                Return New Mobile With {.number = CLng(m), .ok = OK.Maybe}
            Else
                Return Nothing
            End If
        Else
            Return Nothing
        End If
    End Function

Using dr = **ExecuteReader**("select col1 from myTable")
  While dr.Read
      If dr.IsDBNull(0) Then Continue While

      Dim m = GetMobile(CStr(dr(0)))

      If IsNothing(m) Then Continue While

      Select Case m.ok
          Case OK.Yes : N1(m.number) = 1
          Case OK.Maybe : N2(m.number) = 2
      End Select
  End While
End Using

Public Function **ExecuteReader**(sql As String) As SqlDataReader
    Dim conn = New SqlConnection(connString1)
    Dim cmd = New SqlCommand(sql, conn)
    conn.Open()
    Return cmd.ExecuteReader(CommandBehavior.CloseConnection)
End Function

简单的select语句消耗SQL Server中的服务器内存或超时

0 个答案: