The UNIQUE constraint in DB2 ensures that all values in a column (or a combination of columns) are unique, but it allows NULL values. On the other hand, the PRIMARY KEY constraint also enforces uniqueness but does not allow NULL values, and it uniquely identifies each row in a table. 

Normalization is the process of organizing data to minimize redundancy and dependency by dividing large tables into smaller ones. Denormalization, on the other hand, involves adding redundant data to a database for performance reasons, often at the expense of data integrity and storage efficiency. This can lead to faster query performance but may increase the complexity of data management and maintenance. 

Troubleshooting in DB2 focuses on identifying and resolving errors, performance issues, and other problems that may arise in the database environment. This process involves analyzing logs, diagnostic data, and system resources to pinpoint the root cause of the issue and implement appropriate solutions. 

Data security in DB2 is enforced through encryption techniques, ensuring that sensitive information remains protected from unauthorized access. Encryption involves transforming data into a format that can only be read by authorized users, thus safeguarding against data breaches and unauthorized viewing of sensitive data. It serves as a fundamental security measure to maintain confidentiality in DB2 databases. 

Vertical denormalization involves splitting a table vertically to store different attributes in separate tables. This can improve query performance by reducing the number of columns in a table and allowing for more efficient data retrieval. However, it can also lead to increased complexity in database design and management, as it requires managing multiple tables and maintaining relationships between them. Additionally, vertical denormalization can result in increased storage requirements and potential data redundancy if not implemented carefully. Thus, while it can offer benefits in terms of query performance, it requires careful consideration and planning in database design. 

XML and JSON data types in DB2 allow for the storage of semi-structured data. Semi-structured data refers to data that does not conform to a strict schema, allowing for flexibility in data representation. XML and JSON formats are well-suited for representing semi-structured data, and DB2 provides support for storing and querying such data types. 

The primary goal of database recovery in DB2 is to restore the database to a consistent state after a failure. This involves applying transaction logs or backup images to roll forward or roll back changes, ensuring that the database is brought back to a point of consistency and integrity. Recovery processes aim to minimize data loss and downtime, maintaining business continuity. 

Understanding the editions and versions of DB2 is crucial for database administrators as it directly impacts various aspects of database management. It helps them determine the compatibility of their existing systems with specific editions and versions of DB2, ensuring seamless integration and operation. Additionally, knowledge of the feature availability in different editions and versions allows administrators to leverage the functionalities that best suit their organization's requirements. Furthermore, awareness of licensing terms associated with different editions aids in compliance and cost management. Overall, familiarity with editions and versions of DB2 empowers administrators to make informed decisions regarding database deployment, management, and optimization. 

When choosing an encryption algorithm in DB2, it is crucial to consider security requirements. Different encryption algorithms offer varying levels of security, and selecting the appropriate one depends on the sensitivity of the data and the desired level of protection. Other factors such as database size, network latency, and query complexity may influence performance but are secondary to ensuring data security. 

In a distributed environment, views can improve efficiency by reducing the amount of data transferred over the network, thus reducing network traffic.