Which process holds the PostgreSQL database that stores workbook and user metadata when Tableau Catalog is enabled?

The process that holds the PostgreSQL database responsible for storing workbook and user metadata when Tableau Catalog is enabled is the Repository. This component, often referred to as the "Postgres database," stores essential information related to Tableau Server, including details about workbooks, users, and the underlying data assets.

When Tableau Catalog is activated, it extends the functionality of the Repository by adding metadata management capabilities, enabling users to discover, understand, and manage their data assets more effectively. The Repository plays a critical role in ensuring that this metadata is organized and accessible, facilitating features such as data source lineage and impact analysis.

The other processes mentioned do not specifically manage the storage of metadata. SAML Service refers to the security framework that manages authentication, and while Search and Browse relates to how users search for and access content, it is not responsible for storing metadata. VizQL Server is primarily responsible for rendering visualizations and does not handle metadata storage. Thus, the Repository is the correct answer for this question.