Information about the structure of Database is stored in

Concept

In a database management system, every database keeps two separate kinds of stored information: the user data itself, and the metadata that describes how that data is organised. Metadata is "data about data" — the definitions of tables, columns, data types, indexes, constraints, views, and user privileges that together describe the structure of the database.

Application

The repository that the DBMS uses to hold this structural metadata is the data dictionary (also called the system catalog). Whenever a schema object is created or altered, the DBMS records its definition in the data dictionary, and the query processor reads the data dictionary to understand the structure before executing any statement. So information about the structure of the database is stored in the Data Dictionary.

Contrast

• Data File: holds the actual stored rows/records (the content), not the description of how the database is structured.

• Data Components: not a defined DBMS storage object — a generic phrase, not where structure metadata lives.

• Data Model: an abstract design notion (relational, ER, hierarchical) describing how data is conceptually organised; it is a blueprint, not the in-database repository that physically stores the structure definitions.

Therefore the structural metadata of a database resides in its Data Dictionary.