Customizing Windows Registry Settings for Data Access Objects

Note If your application cannot work correctly with the default functionality of the Microsoft Jet database engine, you may have to change the settings in the Windows Registry to suit your needs. The Windows Registry can also be used to tune the operation of the installable ISAM and ODBC driver.

You can modify the settings in the Windows Registry in three different ways. First, you can simply use Regedit.exe to overwrite the default settings which are established when the Microsoft Jet database engine is registered. This method of modification is the least flexible, because all applications which use the Microsoft Jet database engine have these new default settings.

The second method of modifying the Windows Registry settings is to create a Microsoft Jet portion in your application's registry tree to manage the settings for the Microsoft Jet database engine. The easiest way to accomplish this is to export the existing Microsoft Jet key and then import it into your application's tree with the Regedit.exe Export and Import commands. You can then alter any values you want to specify in your new registry tree. If you have supplied any values in the Engines subfolder, Microsoft Jet loads those settings when the application starts. Any values not entered in your client application's registry tree are loaded from shadow settings.

In order for your application to load the appropriate portion of the Windows Registry key you must specify the location with the DAO INIPath property. 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.

Note Although creating a Microsoft Jet portion in your application's registry is more flexible than overwriting the Microsoft Jet default entries, it still requires that you maintain the registry tree. Every time changes are required in the default settings, you will have to edit the Registry. In previous versions of Microsoft Jet these were the only two strategies for modifying the Registry.

DAO 3.5 provides a new way to modify default settings. Registry settings can now be modified at run time with the SetOption method. This is the recommended way to fine tune registry settings for your application. This method is both the most flexible approach and provides the developer with the most control over how the registry is changed. The SetOption method allows the user to specify new settings for any of the following default settings:

• PageTimeout key
  
  
• SharedAsyncDelay key
  
  
• ExclusiveAsyncDelay key
  
  
• LockRetry key
  
  
• UserCommitSync key
  
  
• ImplicitCommitSync key
  
  
• MaxBufferSize key
  
  
• MaxLocksPerFile key
  
  
• LockDelay key
  
  
• RecycleLVs
  
  
• FlushTransactionTimeout key

By using the SetOption method, your application obtains the maximum flexibility and control. This approach allows you to create applications that are easier to maintain and tuned for maximum performance.

You can also edit the Windows Registry to specify the following:

• Settings used for interaction with Microsoft FoxPro, Microsoft Excel, Lotus, Paradox, and dBASE databases. See Initializing the Paradox Database Driver, Initializing the Microsoft FoxPro Database Driver, Initializing the Microsoft Excel Driver, Initializing the Lotus Driver, and Initializing the dBASE Database Driver.
  
  
• Settings used by Microsoft ODBC for interaction with SQL databases. See Initializing the Microsoft ODBC Database Driver.
  
  
• Settings that affect how the Microsoft Jet database engine reads and saves data. See Initializing the Microsoft Jet 2.5 Database Engine Driver, and Initializing the Microsoft Jet 3.5 Database Engine Driver.
  
  
• Settings used to control how the Microsoft Jet database engine interacts with the Internet and Microsoft Exchange. See Initializing the HTML (Internet) Data Source Driver and Initializing the Microsoft Exchange Data Source Driver.
  
  
• Settings used to control how the Microsoft Jet database engine interacts with data imported as plain text. See Initializing the Text Data Source Driver.