why GetFieldValue() is so slow

From:

youngboyxp@gmail.com

Newsgroups:

microsoft.public.vc.mfc

Date:

17 May 2006 07:48:09 -0700

Message-ID:

<1147877289.176588.11150@38g2000cwa.googlegroups.com>

I get connected a vfp6 dbf file, and the total record number is about
50000, I want to export specified field value ( most of their type are
string), and the result is correct, but it works toooooo slow, and I
find the function GetFieldValue takes most time.
my code is:

    while(!m_Rs.IsEOF())
    {
        for(index=0; index < m_ListDest.GetCount(); index++)
        {
            strLine=m_pSortItem[m_pSortList[index]];
            m_Rs.GetFieldValue(m_pSortList[index], strVal);
            strVal.TrimRight(_T(' '));

            if(strVal == "" && m_isFilter)
                continue;

            strLine.Insert(0, _T('['));
            strLine.Insert(strLine.GetLength(), _T("]:"));
            strLine.Insert(strLine.GetLength(), strVal);
            strLine.Insert(strLine.GetLength(), C_Enter);
            strLine.TrimRight(_T(' '));
            fwrite(strLine.GetBuffer(2), sizeof(TCHAR), strLine.GetLength(),
pOutput_file);
        }
        fwrite(&C_Enter, sizeof(TCHAR), 1, pOutput_file);
        m_Rs.MoveNext();
        RecordCount++;

    if(RecordCount == 100)
        {
            Time = GetTickCount() - Time;
            break;
        }

    }

    fclose(pOutput_file);

the Time shows how long will it take, and because it is very slow, I
break it when 100 records have processed.

with the profile mode, it is obvious:

Profile: Function timing, sorted by time
Date: Wed May 17 22:45:38 2006

Program Statistics
------------------
    Command line at 2006 May 17 22:45:
"F:\Training\databasetool\Debug\databasetool"
    Total time: 23453.762 millisecond
    Time outside of functions: 87.659 millisecond
    Call depth: 22
    Total functions: 227
    Total hits: 21321
    Function coverage: 61.2%
    Overhead Calculated 5
    Overhead Average 5

Module Statistics for databasetool.exe
--------------------------------------
    Time in module: 23366.103 millisecond
    Percent of time in module: 100.0%
    Functions in module: 227
    Hits in module: 21321
    Module function coverage: 61.2%

        Func Func+Child Hit
        Time % Time % Count Function
---------------------------------------------------------
   12373.771 53.0 12373.981 53.0 500
CRecordset::GetFieldValue(short,class CString &) (mfcd42d.dll)
    7784.674 33.3 23198.355 99.3 260
CWinThread::PumpMessage(void) (mfc42d.dll)
    2663.737 11.4 2668.303 11.4 1
CFileDialog::DoModal(void) (mfc42d.dll)
     156.984 0.7 158.311 0.7 102
CRecordset::Move(long,unsigned short) (mfcd42d.dll)
     114.126 0.5 114.354 0.5 807
CWnd::DefWindowProcA(unsigned int,unsigned int,long) (mfc42d.dll)
      86.992 0.4 23315.177 99.8 1 CDialog::DoModal(void)
(mfc42d.dll)
      47.422 0.2 15134.158 64.8 1
CDatabasetoolDlg::Export2File(void) (databasetooldlg.obj)
      37.226 0.2 37.226 0.2 1
CDatabase::~CDatabase(void) (mfcd42d.dll)
      21.104 0.1 15328.205 65.6 927 CWnd::OnWndMsg(unsigned
int,unsigned int,long,long *) (mfc42d.dll)
      19.589 0.1 19.589 0.1 1000 CString::TrimRight(char)
(mfc42d.dll)
      13.165 0.1 13.165 0.1 1
CRecordset::~CRecordset(void) (mfcd42d.dll)
       8.671 0.0 8.671 0.0 616 CListBox::GetCount(void)
(mfc42d.dll)
       8.478 0.0 161.017 0.7 1
CDatabasetoolDlg::LoadDatabase(void) (databasetooldlg.obj)
       7.640 0.0 15308.511 65.5 260
CDialog::PreTranslateMessage(struct tagMSG *) (mfc42d.dll)
       3.455 0.0 3.455 0.0 1000
CString::Insert(int,char) (mfc42d.dll)
       3.217 0.0 152.538 0.7 1
CRecordset::Open(unsigned int,char const *,unsigned long) (mfcd42d.dll)
       1.890 0.0 2.012 0.0 21 CWnd::EnableWindow(int)
(mfc42d.dll)

....
I want to know how can I make it faster, any advice is helpful, and
thank you!