WBJECA 2025 — Computer PYQ

A data dictionary (or metadata repository) is a centralized, read-only file or database that stores "data about data." It is essential for the DBMS to manage the structure and integrity of the database.

It maintains detailed information, including:

• Field Names: The identifiers for every attribute in the database.

• Data Types: The classification of data (e.g., integer, string, date) for each field.

• Field Width/Size: The storage requirements or constraints for each field.

• Other Metadata: Constraints, default values, indices, and relationships between tables.

Mathematically, we can view the contents of a data dictionary ($DD$) as the union of all metadata attributes ($M$) for every field ($f$) in the database system ($D$):

$$\text{Contents}(DD)=\bigcup _{f\in D}\{{\text{Name}}_f,{\text{DataType}}_f,{\text{Width}}_f,\dots \}$$

Therefore, the representation of the data dictionary's completeness is:

$$\text{Metadata}=\text{Names}\cup \text{DataTypes}\cup \text{Widths}\cup \text{Constraints}$$

Since the data dictionary encompasses all these descriptive elements, "All of these" is the correct choice.