Configurable Performance Settings

Settings in the Engines subkey of the Windows Registry control how Microsoft Jet uses memory and performs other aspects of its operations. Microsoft Jet automatically provides default settings that usually give the best performance for most common database operations. However, depending on what kind of operations your application performs and how much memory is available at any given time, you may be able to improve performance by adjusting Microsoft Jet registry settings.

Keep in mind that the optimum value for a setting can change from computer to computer, and can change depending on how much memory is available, the kind of operation the user is performing, or the level of activity in the database at any given time. Using a system and working environment that’s as much like your typical user’s system as possible, experiment with these settings to find out what works best.

If you decide to change any of the Microsoft Jet registry settings in the Windows Registry, you have four options. You can:

• Use the SetOption method in code to temporarily modify Microsoft Jet registry settings at run time. This is the recommended method for adjusting the Microsoft Jet registry settings in the Engines subkey. For more information on using the SetOption method, see “Using the SetOption Method to Control Registry Settings” later in this chapter.
  
  
• Create a custom set of registry keys, called a user profile, that contains settings to override default registry settings.

  To have these settings affect only a particular Microsoft Access database application or session of Microsoft Access, use the /profile command-line option when starting Microsoft Access to specify the user profile you want to use. If you are creating a Microsoft Access run-time application using the Setup Wizard available in Microsoft Office 97, Developer Edition, you can use the wizard to define custom registry settings that are created when your application is installed.

  To have these settings affect any Visual Basic or Visual Basic for Applications application, specify the location of the user profile by using the IniPath property in your application’s code. Your application must set the IniPath property before executing any other DAO code. The scope of this setting is limited to your application and can’t be changed without restarting your application.

• Change the default values for Microsoft Jet settings in the \HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Jet\3.5\Engines\Jet 3.5 key.

  These defaults are written when Microsoft Jet is installed. Changes made to settings in this key can affect all applications that use Microsoft Jet 3.5, such as Microsoft Access 97, Visual Basic version 5.0, or Microsoft Excel 97. Make changes to values in this key only if you want to affect all the applications that use Microsoft Jet 3.5 on a user’s computer.

• Create a Jet 3.5 subkey in the \HKEY_LOCAL_MACHINE\SOFTWARE
  \Microsoft\Office\8.0\Access\Jet\3.5\Engines key, and then add values for any default setting you want to override.

  These changes affect only Microsoft Access 97.

See Also For information on user profiles or changing Microsoft Access registry settings, search the Microsoft Access Help index for “user profiles” or “Registry .” For information on the IniPath property or SetOption method, search the DAO Help index for “IniPath property” or “SetOption method.”