DOCUMENT:Q173646 11-SEP-1997 [vbwin] TITLE :HOWTO: Use a Custom Jet Profile to Alter Data Access Behavior PRODUCT :Microsoft Visual Basic for Windows PROD/VER:WINDOWS:4.0,5.0,7.0,97 OPER/SYS:WINDOWS KEYWORDS:APrgDataAcc vb416 VB4WIN vb5all VBKBEnv VBKBRegistry ====================================================================== --------------------------------------------------------------------- The information in this article applies to: - Microsoft Visual Basic Professional and Enterprise Editions for Windows, version 5.0 - Microsoft Visual Basic Professional and Enterprise Editions, 32-bit only, for Windows, version 4.0 - Microsoft Access versions 7.0, 97 --------------------------------------------------------------------- SUMMARY ======= You can edit the Jet Registry keys to alter the data access behavior of the Microsoft Jet database engine. However, doing so affects all Jet-based applications, and may have unintended negative consequences for some. By using custom profiles, you can tune Jet on a per-application basis. MORE INFORMATION ================ In 16-bit versions of Visual Basic and Microsoft Access, Jet settings are stored in an .ini file (for example, Msaccess.ini or Msacc20.ini). You can provide a custom .ini file with your application that contains settings specific to your application. The 32-bit versions of Jet read their settings from the registry. In Visual Basic 4.0 and 5.0, Jet versions 3.0 and 3.5 use the default registry location: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Jet\3.0 -or- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Jet\3.5 If using Microsoft Access, settings are read from the following branch first, and then the default location (above) is used for any additional values: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Access\7.0\Jet\3.0 -or- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\8.0\Access\Jet\3.5 To prevent multiple applications from making custom changes to these settings and negatively impacting other Jet-based programs, the application can tell Jet to read its settings from a different branch of the registry. These alternate branches are known as Profiles. You don't have to reproduce the entire registry branch in your profile. Values you specify in your custom profile override values specified in the default registry location, which in turn override internal Jet default values. Example Profile --------------- NOTE: Inadvertent changes to the Registry could affect the stability of the operating system. You should back up the registry prior to proceeding. This example illustrates registry changes for a custom profile that lowers the LockRetry setting from the default value of 20 to 5. 1. In the Registry Editor, expand HKEY_LOCAL_MACHINE\SOFTWARE and add key values for your company name (MyCorp), application name (MyApp), and version (1.0): HKEY_LOCAL_MACHINE\SOFTWARE\MyCorp\MyApp\1.0 2. The above is sufficient for Visual Basic, but to maintain compatibility with Microsoft Access applications, add keys for "Jet" and "3.0" or "3.5": HKEY_LOCAL_MACHINE\SOFTWARE\MyCorp\MyApp\1.0\Jet\3.0 -or- HKEY_LOCAL_MACHINE\SOFTWARE\MyCorp\MyApp\1.0\Jet\3.5 3. This is an empty Profile. From here, add keys and values that affect Jet's behavior. To make the LockRetry changes, add the keys "Engines" and "Jet": HKEY_LOCAL_MACHINE\SOFTWARE\MyCorp\MyApp\1.0\Jet\3.0\Engines\Jet -or- HKEY_LOCAL_MACHINE\SOFTWARE\MyCorp\MyApp\1.0\Jet\3.5\Engines\Jet Then, add a REG_DWORD Value, called LockRetry, and a value of 5. The profile is complete. Using the Profile in Visual Basic --------------------------------- To use the profile in Visual Basic, set DBEngine.IniPath to the profile name prior to using any database functionality: In Visual Basic 4.0: DBEngine.IniPath = _ "HKEY_LOCAL_MACHINE\SOFTWARE\MyCorp\MyApp\1.0\Jet\3.0" In Visual Basic 5.0: DBEngine.IniPath = _ "HKEY_LOCAL_MACHINE\SOFTWARE\MyCorp\MyApp\1.0\Jet\3.5" Using the Profile in Microsoft Access ------------------------------------- Unlike visual Basic, where you can set the profile name programmatically, Jet is already initialized by the time your Microsoft Access code is running. To specify a profile name, you need to add another registry key to specify a "friendly" profile name and use a command-line switch when starting Microsoft Access: 1. Expand the following registry branch: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Access\7.0 -or- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\8.0\Access 2. Add a key "Profiles". HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Access\7.0\Profiles -or- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\8.0\Access\Profiles 3. Add a REG_SZ value with the name being your "friendly" profile name (for example, MyProfile) and the value being the registry branch where the profile settings are located. For example: Name: MyProfile Type: REG_SZ Value: HKEY_LOCAL_MACHINE\SOFTWARE\MyCorp\MyApp\1.0 4. Start Microsoft Access with the command-line option: MSACCESS.EXE /PROFILE "MyProfile" MYDATABASE.MDB Microsoft Access 95 will automatically choose the ...\Jet\3.0 branch, Microsoft Access 97 will automatically choose the ...\Jet\3.5 branch, in Visual Basic you must specify the complete profile path. 5. Because you can't guarantee that Microsoft Access was started using the correct profile, you can check your startup code to see if the user started the application properly or just double-clicked the icon for the .mdb file. For example: If SysCmd(acSysCmdProfile) <> "MyProfile" Then MsgBox "To use this database, run MyApp from the Start Menu" DoCmd.Quit acExit End If Compatibility with Earlier Jet Databases ---------------------------------------- If the database you're opening is used by earlier versions of Jet (1.0, 1.1, 2.0, or 2.5), Microsoft Jet 3.x doesn't read these files directly. It uses an Installable ISAM engine in the same way it would when reading a dBase or Paradox file. For example, to set the LockRetry value for accessing a Jet 2.x database, add the Value to the following location: HKEY_LOCAL_MACHINE\SOFTWARE\MyCorp\MyApp\1.0\Jet\3.0\Engines\Jet 2.x\ISAM You still only reference the profile location as indicated in the Microsoft Access and Visual Basic usage sections above. For example: In Visual Basic: DBEngine.IniPath = _ "HKEY_LOCAL_MACHINE\SOFTWARE\MyCorp\MyApp\1.0\Jet\3.0" -or- DBEngine.IniPath = _ "HKEY_LOCAL_MACHINE\SOFTWARE\MyCorp\MyApp\1.0\Jet\3.5" In Microsoft Access: Value: HKEY_LOCAL_MACHINE\SOFTWARE\MyCorp\MyApp\1.0 Table of Engine Keys -------------------- The following table lists registry branches for the Jet 3.x engine and the various other engines: Engine Registry Branch ---------------------------------------------------- Jet 3.x ...\Engines\Jet Jet 2.x ...\Engines\Jet 2.x\ISAM ODBC ...\Engines\ODBC Xbase ...\Engines\Xbase Paradox ...\Engines\Paradox Excel ...\Engines\Excel Lotus ...\Engines\Lotus Text ...\Engines\Text Jet 3.5 Notes ------------- With Jet 3.5, you can tune some values dynamically using the new SetOption method of the DBEngine object. This means you can use some values for one part of your program, that is, to favor a bulk update, while using other values in another part of your program, that is, to favor interactive data entry. Using DBEngine.SetOption affects only the current instance of your program. It can be used in Microsoft Access 97 and Visual Basic 5.0. The following table lists the settings you can change: Setting Constant --------------------------------------------------- PageTimeout dbPageTimeout SharedAsyncDelay dbSharedAsyncDelay ExclusiveAsyncDelay dbExclusiveAsyncDelay LockRetry dbLockRetry UserCommitSync dbUserCommitSync ImplicitCommitSync dbImplicitCommitSync MaxBufferSize dbMaxBufferSize MaxLocksPerFile dbMaxLocksPerFile LockDelay dbLockDelay RecycleLVs dbRecycleLVs FlushTransactionTimeout dbFlushTransactionTimeout Usage: DBEngine.SetOption dbMaxBufferSize, 128 REFERENCES ========== For a complete list of Jet engine registry settings and their descriptions, refer to Appendix C of the Microsoft Jet Database Engine Programmer's Guide or the Help topic: Customizing Windows Registry Settings for Data Access Objects For help with Microsoft Access Profiles, see the Help topic "Profiles, User." To programmatically read/write registry settings, please refer to the following Knowledge Base article: ID: Q145679 Title: How to Use the Registry API to Save and Retrieve Setting 4. For more information on DBEngine.SetOption, see the Help topic: Customizing Windows Registry Settings for Data Access Objects Additional query words: vb5 vb4 ====================================================================== Keywords : APrgDataAcc vb416 VB4WIN vb5all VBKBEnv VBKBRegistry Component : jet Version : WINDOWS:4.0,5.0,7.0,97 Platform : WINDOWS Issue type : kbhowto ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 1997.