What is the purpose of a security predicate function in Row-Level Security (RLS)?

• A. It enables type conversions in predicate functions.
• B. It logs security events.
• C. It determines whether a row is accessible to a user based on certain conditions.
• D. It allows users to run ad hoc queries.

Answer: (C)

In Row-Level Security, the security predicate function defines whether a given row should be visible to the current user by evaluating conditions tied to that user’s identity or context. For every row a query touches, the predicate is evaluated and returns true if the row is accessible or false if it should be hidden. This is what enforces rules like “a user can only see data from their own department” by comparing the row’s attributes to the user’s context (for example, their department or role) obtained from the session. The function’s purpose is not about type conversions, logging security events, or enabling ad hoc queries—it's specifically about filtering data so users only access rows they are authorized to see.