Slower performance in Access-based or Jet database-based programs after you upgrade from Windows NT 4.0 to Windows 2000 or to Windows XP

Symptoms

After you upgrade your computer from Microsoft Windows NT 4.0 to Microsoft Windows 2000 or to Microsoft Windows XP Professional, you may experience slower performance in Microsoft Access-based or Jet database-based programs.

Cause

This issue may occur if one or more of the following conditions are true:
  • You are working with a split database, and the backend database file resides in a folder that has a name that is longer than 8 characters. For example, the backend database file resides in a folder that has a name that is similar to the following:
    BigFolderName
  • You are working with a split database, and the name of the backend database file is longer than 8 characters excluding the three-character .mdb file name extension. For example, the backend database file has a name that is similar to the following:
    BigDatabaseFileName.mdb
  • You are working with a database that is not split, and the name of the database file does not follow the 8.3 naming convention. Or the database is stored in a folder that has a long name.
The caching design of the Workstation service in Windows 2000 and in later versions of Windows is different from the caching design of the Workstation service in earlier versions of Windows.

In Windows 2000 and in later versions of Windows, the caching design of the Workstation service has been changed to favor database integrity in a multi-user environment. This design change causes a delay when Jet makes API calls to retrieve information about the long folder name or about the long file name.
For more information, click the following article number to view the article in the Microsoft Knowledge Base:

889588 How to optimize Office Access and Jet database engine network performance with Windows 2000-based and Windows XP-based clients

Resolution

Microsoft provides programming examples for illustration only, without warranty either expressed or implied. This includes, but is not limited to, the implied warranties of merchantability or fitness for a particular purpose. This article assumes that you are familiar with the programming language that is being demonstrated and with the tools that are used to create and to debug procedures. Microsoft support engineers can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific requirements.

If you are working with a split database, you can resolve this issue by relinking your existing Jet tables. To do this, create code to send a short representation of the long folder name to the Windows API. This resolution requires your backend database to have a file name that follows the 8.3 naming convention. To create this code, follow these steps in the front-end database:
  1. Set a reference to Microsoft ADO Ext 2.5 (or to a later version of ADO).
  2. Add the following code to a new module.
    Declare Function GetShortPathName Lib "kernel32" _
    Alias "GetShortPathNameA" (ByVal lpszLongPath As String, _
    ByVal lpszShortPath As String, ByVal cchBuffer As Long) As Long

    Function RefreshLinks()
    On Error GoTo ErrorHandler

    'Define the ADOX Catalog object.
    Dim objCat As New ADOX.Catalog
    'Define the ADOX Table object.
    Dim objTbl As ADOX.Table

    'Database name of the linked table.
    Dim strFilename As String
    'Path and database name of the linked table.
    Dim strFullName As String

    Dim blnIsMapi As Boolean
    Dim blnIsImex As Boolean
    Dim blnIsTemp As Boolean
    Dim blnLongFileName As Boolean
    Dim blnFailedLink As Boolean
    Const srtImex = "IMEX"
    Const strMapi = "MAPILEVEL="

    'Open the catalog.
    objCat.ActiveConnection = CurrentProject.Connection

    'Loop through the table collection and update the linked tables.
    For Each objTbl In objCat.Tables
    'Verify that the table is a linked table.
    If objTbl.Type = "LINK" = True Then
    blnIsTemp = objTbl.Properties("Temporary Table") Or Left(objTbl.Name, 1) = "~"
    blnIsImex = (InStr(1, objTbl.Properties("Jet OLEDB:Link Provider String"), srtImex, vbTextCompare) > 0)
    blnIsMapi = (InStr(1, objTbl.Properties("Jet OLEDB:Link Provider String"), strMapi, vbTextCompare) > 0)

    If Not blnIsTemp And Not blnIsImex And Not blnIsMapi Then
    'Verify that the table is a Jet table.
    strFullName = objTbl.Properties("Jet OLEDB:Link Datasource")
    strFilename = Mid(strFullName, InStrRev(strFullName, "\", _
    Len(strFullName)) + 1, Len(strFullName))
    'Determine whether the database exists.
    If DoesFileExist(strFullName) = True Then
    objTbl.Properties("Jet OLEDB:Link Datasource") = GetShortName(strFullName)
    'Update the link by using the short path name.
    Else
    MsgBox "Cannot update: '" & objTbl.Name & "'" & String(2, vbCrLf) & "File not found: " & vbCrLf & strFullName
    blnFailedLink = True
    End If
    If InStr(strFilename, ".") > 9 Then blnLongFileName = True
    End If
    End If
    Next

    If blnFailedLink = False Then
    If blnLongFileName = True Then
    MsgBox "The table links were successfully updated, but the name of the backend database file does not follow 8.3" & _
    vbCrLf & "Please rename the file, relink the tables, and then run the procedure again.", vbExclamation
    Else
    MsgBox "The links were successfully updated!!! ", vbInformation
    End If
    Else
    MsgBox "The links were not successfully updated." & vbCrLf & "Please verify you table links.", vbExclamation
    End If

    ExitHandler:
    Exit Function

    ErrorHandler:
    MsgBox Err.Description & " " & Err.Number
    Resume ExitHandler

    End Function
    Function GetShortName(ByVal sLongFileName As String) As String
    Dim lRetVal As Long, sShortPathName As String, iLen As Integer
    'Set up a buffer area for the API function call return.
    sShortPathName = Space(255)
    iLen = Len(sShortPathName)

    'Call the function.
    lRetVal = GetShortPathName(sLongFileName, sShortPathName, iLen)
    'Remove unwanted characters.
    GetShortName = Left(sShortPathName, lRetVal)
    End Function

    Function DoesFileExist(strFileSpec As String) As Boolean
    'Return True if the file that is specified in the
    'strFilespec argument exists.
    'Return False if strFileSpec is not a valid
    'file or if strFileSpec is a directory.
    Const INVALID_ARGUMENT As Long = 53
    On Error GoTo DoesfileExist_Err
    If (GetAttr(strFileSpec) And vbDirectory) <> vbDirectory Then
    DoesFileExist = CBool(Len(Dir(strFileSpec)) > 0)
    Else
    DoesFileExist = False
    End If
    DoesfileExist_End:
    Exit Function
    DoesfileExist_Err:
    DoesFileExist = False
    Resume DoesfileExist_End
    End Function
  3. Run the RefreshLinks function. To do this, follow these steps:
    1. In Visual Basic Editor, click Immediate Window on the View menu.
    2. In the Immediate window, type RefreshLinks. Then, press ENTER.
The RefreshLinks function loops though the linked Jet tables in a database and verifies whether the link is valid. If the link is valid, this code uses the Windows API function GetShortPathName to create a short name that follows the 8.3 naming convention.
For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

142982 How Windows generates 8.3 file names from long file names

This code then updates the link by using a path that includes the new short name. If the link points to a backend database file that does not follow the 8.3 naming convention, this code generates a message to suggest that you rename the backend database file.

Status

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

Note If you use Windows XP, you may improve performance by applying Microsoft Windows XP Service Pack 2 (SP2).

More Information

For additional information, click the following article numbers to view the articles in the Microsoft Knowledge Base:

209862 How to relink backend tables with the common dialog control in Access 2000

175512 How to get a short file name from a long file name

Proprietà

ID articolo: 891176 - Ultima revisione: 17 set 2011 - Revisione: 1

Feedback