Why are the data dictionary contents often hidden from users in DBMS?

• A. To prevent accidental destruction of its contents
• B. To improve query performance
• C. To hide all schema details from users
• D. To reduce storage space

Answer: (A)

The key idea is that the data dictionary is the system catalog that stores metadata about every database object—tables, columns, data types, constraints, privileges, and more. Because this catalog is central to the DBMS’s operation, exposing its contents to regular users creates a real risk: accidental or unauthorized changes could corrupt definitions, break dependencies, or undermine security. By hiding the data dictionary from everyday users, the system reduces the chance of accidental destruction or modification, while still allowing authorized users to access needed metadata through controlled interfaces. The other options don’t capture the main purpose: hiding the dictionary won’t notably boost query performance, it isn’t about hiding all schema details (controlled access is often provided), and it doesn’t serve to save meaningful storage space.