XMLQUERY in DB2 allows developers to extract specific information from an XML document. It provides powerful querying capabilities, enabling developers to navigate and retrieve data from complex XML structures efficiently. With XMLQUERY, developers can specify XPath expressions to pinpoint the desired data elements within the XML document, facilitating easy integration of XML data into their applications. 

The Log Manager in DB2's architecture facilitates transaction logging and recovery. It records all changes made to the database in a sequential log, allowing for rollback and recovery in case of system failures or errors. This ensures database consistency and durability by providing a means to restore the database to a consistent state after a failure. The log manager also aids in database replication and point-in-time recovery. 

Views in DB2 restrict access to specific columns or rows of a table, thus enhancing data security by only allowing authorized users to see limited portions of the data. This helps in controlling access to sensitive information and ensures data privacy. 

Indexed views in DB2 can significantly improve performance by precomputing and storing the results of the view in the form of an index. This allows for faster data retrieval, especially for complex queries involving joins and aggregations. Materialized views can also be used for performance optimization, but they store the entire result set of the view in a physical table, which might incur overhead for maintenance and storage. 

Roles in DB2 security serve to facilitate group-based permissions, allowing administrators to assign sets of privileges to groups of users, simplifying access management and enhancing security. 

In denormalization, one action taken to reduce the number of joins in SQL queries is to combine multiple tables into one. By consolidating related data from different tables into a single denormalized table, the need for joining tables in SQL queries is minimized. This approach simplifies query formulation and execution, leading to improved performance, especially for read-heavy workloads. However, it's essential to carefully design the denormalized schema to avoid excessive redundancy and maintain data consistency. 

Common methods used to maintain data integrity in a DB2 database include constraints, triggers, and referential integrity. Constraints ensure that data meets certain criteria or rules before being inserted or updated in a table. Triggers are actions that are automatically performed in response to certain events, such as inserting, updating, or deleting data from a table. Referential integrity ensures that relationships between tables are enforced, preventing orphan records and maintaining consistency. These methods help to ensure that the data remains accurate, consistent, and reliable. 

The FOREIGN KEY constraint in DB2 enforces referential integrity, ensuring that values in a column (or columns) of one table match values in another table's primary key or unique key. This maintains consistency and relationships between related tables. 

High availability in a DB2 environment primarily aims to reduce downtime. This means ensuring that the system is accessible and operational even in the event of hardware failures, software failures, or other disruptions. By minimizing downtime, businesses can maintain continuity of operations and avoid costly interruptions to their services. 

The DB2 Command Line Processor (CLP) provides a text-based interface for database administration. It allows users to interact with the database by typing commands directly into the command line interface. This interface is commonly used by database administrators and developers to perform various tasks such as executing SQL statements, managing database objects, and monitoring database performance.