When choosing a clustering key in DB2, it's essential to consider various factors such as the cardinality of the key (i.e., the uniqueness of values), access patterns of queries (i.e., how frequently certain data is accessed), and the distribution of data across partitions. These factors influence query performance, as they affect the efficiency of data retrieval and storage. 

DB2 enforces access control on database objects primarily through user authentication, where only authorized users with appropriate privileges can access and manipulate the data stored within the database. 

DB2 optimizes the execution plan when querying a view to retrieve data more efficiently. By analyzing the underlying tables and the view definition, DB2 can optimize join paths, access methods, and other factors to enhance query performance. 

OLE DB (Object Linking and Embedding Database) plays a crucial role in integrating DB2 with Microsoft applications. It provides a set of COM (Component Object Model) interfaces that enable applications to access and manipulate data from various data sources, including DB2. OLE DB offers a unified way for Microsoft applications such as Excel, Access, and SQL Server to communicate with DB2 databases, allowing seamless data exchange and integration. By using OLE DB, developers can build robust and scalable solutions that leverage the capabilities of both DB2 and Microsoft applications. 

A cursor with a FOR UPDATE clause allows for updating data. This clause is used to lock the rows returned by the cursor for update operations, enabling modifications to the data directly through the cursor. It is commonly used in scenarios where data modifications need to be made based on specific criteria. 

In DB2, a view represents a virtual table that does not store data physically but rather provides a logical representation of data stored in one or more underlying tables. Queries against views are processed by fetching data from the underlying tables based on the view's definition. 

Eclipse is commonly used alongside IBM Data Studio for developing and managing DB2 databases. IBM Data Studio is built on top of the Eclipse platform, providing a seamless integration of development tools specifically tailored for working with DB2 databases. 

The SQL statement used to create a user-defined function in DB2 is "CREATE FUNCTION". This statement allows developers to define custom functions tailored to specific requirements. 

DB2 primarily uses a hash key for data distribution in partitioning. This involves hashing the data using a hash function and distributing it across partitions based on the result of the hash function. 

DB2 provides built-in functions specifically designed for querying and manipulating semi-structured data types such as XML and JSON. These functions enable developers to perform various operations on semi-structured data stored in DB2 databases, such as extracting values, navigating hierarchical structures, and transforming data formats.