Which requirement within large, complex databases ensures users have limited access to the database?

The requirement that ensures users have limited access to a database is grounded in the principle of authorization. Authorization is a security mechanism that determines what resources a user can access and what actions they can perform within a system. In the context of large, complex databases, this means that specific users or user groups are granted permissions based on their needs and roles within the organization. Effective authorization policies help prevent unauthorized access to sensitive data, thereby protecting the integrity and confidentiality of the information stored in the database.

Implementing robust authorization frameworks, such as role-based access control or attribute-based access control, allows administrators to finely tune access levels for each user and monitor their activities. This is crucial for maintaining both security and compliance with data protection regulations, especially in environments where sensitive information is being managed.

The other requirements mentioned—recovery, performance, and confidentiality—play important roles within database management but do not specifically address the limitation of user access. Recovery focuses on the database's ability to restore data after a failure, performance concerns the efficiency and speed of database operations, and confidentiality pertains to the protection against unauthorized disclosure of information. Each of these is essential, but authorization specifically relates to controlling user access levels.