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. 

RESTful APIs offer a modern and flexible approach to data access. They facilitate communication between different systems over the internet, allowing clients to interact with databases through standard HTTP methods. With RESTful APIs, developers can access and manipulate data stored in DB2 databases from various platforms and programming languages, fostering interoperability and ease of integration. This approach simplifies application development by providing a uniform interface for accessing database resources, promoting agility and scalability in software development projects. 

When designing triggers in DB2, it's crucial to consider various factors to avoid performance issues. One such factor is the frequency of trigger execution. Triggers that fire frequently can impact database performance, especially if they involve complex logic or operations on large data sets. The complexity of trigger logic is another consideration. Complex triggers may require more CPU and memory resources, leading to performance degradation. Additionally, the size of the affected data set can impact trigger performance, as triggers must process all affected rows. Therefore, it's essential to carefully analyze these factors and optimize trigger design to minimize performance overhead in a DB2 environment. 

The DB2 Command Line Processor (CLP) offers batch capabilities for executing SQL commands and scripts. It allows users to run SQL commands and scripts in batch mode, enabling automation and efficient execution of tasks without the need for manual intervention. 

The MAX() function retrieves the largest value from a specified column in a table. On the other hand, the MIN() function retrieves the smallest value from a specified column. Both functions are aggregate functions commonly used in SQL queries to perform calculations on sets of values. The key difference lies in the values they retrieve based on the specified column. 

Clustering in DB2 is primarily used for optimizing query performance. It involves physically storing related rows together on disk to minimize disk I/O operations and improve the efficiency of data retrieval during queries. 

Attributes within tags in DB2 serve the purpose of providing additional information about the data contained within the tags. This could include metadata such as data types, lengths, or any other relevant details about the data being represented. These attributes enhance the clarity and context of the data within the XML document. 

The Reorg utility in DB2 is responsible for reorganizing the data and indexes within a tablespace or a table to optimize storage allocation and improve performance. During this process, the utility rearranges data pages, rebuilds indexes, and updates statistics, resulting in improved storage efficiency and query performance. By periodically running the Reorg utility, DBAs can ensure that data is stored in the most optimal manner, reducing storage overhead and enhancing overall system performance.