Chapter 19: OLE DB Services

OLE DB Programmer's Reference

OLE DB provides common services to enhance the native functionality and performance of OLE DB providers. These services include the Client Cursor Engine, which enables OLE DB consumers to scroll or find over the rowsets of providers that do not natively support such functionality, as well as performance and scaling features such as resource pooling and automatic transaction enlistment within a Microsoft Windows NT /Windows  2000 Component Services (or Microsoft Transaction Server, if you are using Windows NT) environment.

OLE DB services are automatically enabled when a consumer invokes a provider by calling an IDataInitialize or IDBPromptInitialize method. Consumers can also enable OLE DB services by calling CoCreateInstance, passing the CLSID of the OLE DB Initialization Component as an argument. (OLE DB services are not enabled by calling CoCreateInstance to invoke the provider based on the provider's CLSID.) For more information, see "Creating Data Source Objects" in Chapter 2: Data Source and Session Objects.

The following sections describe OLE DB resource pooling and explain how to use it and other services in OLE DB providers and consumers:

• Resource Pooling
• Writing Scalable OLE DB Providers
• How Providers Work Effectively with Resource Pooling
• How Consumers Use Resource Pooling
• Automatic Transaction Enlistment
• Enabling and Disabling Individual OLE DB Services
• Setting Provider Service Defaults
• Overriding Provider Service Defaults

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