Q149618: PRB: PageTimeout Defaults to Five Seconds in Jet 3.0
Article: Q149618
Product(s): Microsoft Visual Basic for Windows
Version(s): 4.0,5.0,6.0
Operating System(s):
Keyword(s): kbVBp500 kbVBp600 kbGrpDSVBDB
Last Modified: 11-JAN-2001
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The information in this article applies to:
- Microsoft Visual Basic Standard Edition, 32-bit, for Windows, version 4.0
- Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0
- Microsoft Visual Basic Learning Edition for Windows, versions 5.0, 6.0
- Microsoft Visual Basic Professional Edition for Windows, versions 5.0, 6.0
- Microsoft Visual Basic Enterprise Edition for Windows, versions 5.0, 6.0
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SYMPTOMS
========
When two applications are trying to gain access to the same database using Jet
3.x, any data entered from the other user will not be updated for five seconds
even after the code re-queries the database.
RESOLUTION
==========
NOTE: Before running workaround, see Steps to Reproduce Behavior below.
If you are using Jet 3.0, a key needs to be added to the registry under:
\\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Jet\3.0\Engines
The key should be called JET. A New DWORD value called PageTimeout also needs to
be added. Modify the PageTimeout entry to set a decimal value in milliseconds
for this entry from a Visual Basic 32-Bit Application.
If you are using Jet 3.50 or Jet 3.51, then the following key will already exist
in the registry:
\\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Jet\3.5\Engines\Jet 3.5
Furthermore, a key called PageTimeout will already exist under this key. The
value of the PageTimeout key will need to be modified from five seconds to .5
seconds.
In order to do this within a Visual Basic project, open a new Standard.exe Visual
Basic project. Place the following code into the General Declarations of a
Form:
Option Explicit
Private Const HKEY_LOCAL_MACHINE = &H80000002
Private Const REG_DWORD = 4&
Private Const REG_OPTION_NON_VOLATILE = 0&
Private Const KEY_ALL_ACCESS = &HF003F
Private Declare Function RegQueryValueEx Lib "advapi32.dll" Alias _
"RegQueryValueExA" (ByVal hKey As Long, ByVal lpValueName As String, _
ByVal lpReserved As Long, lpType As Long, lpData As Any, _
lpcbData As Long) As Long
Private Declare Function RegCloseKey Lib "advapi32.dll" _
(ByVal hKey As Long) As Long
Private Declare Function RegOpenKeyEx Lib "advapi32.dll" Alias _
"RegOpenKeyExA" (ByVal hKey As Long, ByVal lpSubKey As String, _
ByVal ulOptions As Long, ByVal samDesired As Long, phkResult As Long) _
As Long
Private Declare Function RegCreateKeyEx Lib "advapi32.dll" Alias _
"RegCreateKeyExA" (ByVal hKey As Long, ByVal lpSubKey As String, _
ByVal Reserved As Long, ByVal lpClass As String, ByVal dwOptions _
As Long, ByVal samDesired As Long, ByVal lpSecurityAttributes As Long, _
phkResult As Long, lpdwDisposition As Long) As Long
Private Declare Function RegSetValueEx Lib "advapi32.dll" Alias _
"RegSetValueExA" (ByVal hKey As Long, ByVal lpValueName As String, _
ByVal Reserved As Long, ByVal dwType As Long, lpValue As Long, _
ByVal cbData As Long) As Long
Dim lpszKey As String
Dim lpszSubKey As String
Dim lpValueName As String
Dim phkResult As Long
Dim ReturnValue As Long
Dim lresult As Long
Dim lretval As Long
Dim ptimeout As Long
Place the following code into the Form Load of the Form:
'Desired PageTimeout
ptimeout = 500 'This is .5 seconds
'Set up strings
lpszSubKey = "Software\Microsoft\Jet\3.0\Engines\Jet"
' for VB5 or VB6, lpszSubKey should equal:
' lpszSubKey = "Software\Microsoft\Jet\3.5\Engines\Jet 3.5"
lpszKey = HKEY_LOCAL_MACHINE
lpValueName = "PageTimeout"
'If the key exists open it or if not we will create it
lresult = RegCreateKeyEx(lpszKey, lpszSubKey, 0&, vbNullString, _
REG_OPTION_NON_VOLATILE, KEY_ALL_ACCESS, 0&, phkResult, lretval)
'Search for lpValueName entry in lpszsubkey
lresult = RegQueryValueEx(phkResult, lpValueName, 0, REG_DWORD, _
lretval, 4)
'Check return value accordingly
Select Case lresult
Case 0
'Success
'Comment next line if you don't want to change the value if exists
lresult = RegSetValueEx(phkResult, lpValueName, 0, REG_DWORD, _
ptimeout, 4)
Case 2
'If entry doesn't exist create it and set it to ptimeout
lresult = RegSetValueEx(phkResult, lpValueName, 0, REG_DWORD, _
ptimeout, 4)
If lresult Then MsgBox "Could not set PageTimeout. Error:" & _
Str$(lresult)
Case Else
MsgBox "Unexpected Return Value:" & Str$(lresult)
End Select
'Close the updated key
lresult = RegCloseKey(phkResult)
STATUS
======
This behavior is by design. Microsoft Jet version 3.0's PageTimeout property
defaults to 5 seconds. This is not the case with Jet version 2.5 that defaults
to .5 seconds.
MORE INFORMATION
================
Steps to Reproduce Behavior
---------------------------
NOTE: Perform these steps before running the workaround above.
With the Microsoft DAO 3.x Object Library selected in Tools REFERENCES
1. Start a new standard.exe project in Visual Basic. Form1 is created by
default. Add a Data Control (Data1) to Form1. Bind the Data Control to a
Database and set a text box to display one of the fields in the database. Add
a button to do a Data1. Refresh and make an .exe.
2. Run two instances of the .exe, modify the data in one instance, and
immediately click the refresh in the other instance. Notice that it takes
five seconds for the data to be updated.
Additional query words: kbVBp400 kbVBp500 kbVBp600 kbdse kbDSupport kbVBp kbDAO kbRegistry
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Keywords : kbVBp500 kbVBp600 kbGrpDSVBDB
Technology : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVBA500 kbVBA600 kbVB500 kbVB600 kbVB400Search kbVB400
Version : :4.0,5.0,6.0
Issue type : kbprb
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