What is a description of how a database is physically stored called?

The description of the physical storage method of the database is called the "internal schema". The internal schema gives the physical storage structure and physical access methods of the database, such as the file structure, index, clustering, hash and other access methods and access paths of data storage. The physical properties of the internal schema are mainly reflected in the operating system and file level. superior.

Internal Schema (Internal Schema) is also called Physical Schema (Physical Schema). It gives the database physical storage structure and physical access methods, such as data storage The file structure, index, clustering, hash and other access methods and access paths, the physical nature of the internal model is mainly reflected in the operating system and file level.

The internal schema is also called the storage schema, which corresponds to the physical level. It is the internal representation or underlying description of all data in the database. It is the lowest level logical description of the database. It describes the storage of data on the storage medium. The method and physical structure correspond to the database actually stored on the external storage medium.

The internal schema is described and defined by the internal schema description language, the organization of all internal record types, indexes and files, and data control details. It is the storage view of the database.

The internal schema is a description and expression of the specific implementation of the database on physical storage. It specifies the physical organization of data on storage media, record addressing technology, defines the size of physical storage data blocks, overflow handling methods, etc.

Corresponding to the conceptual schema, the internal schema is described by the data storage description language. The three-level schema structure of the database system distinguishes the global logical structure and physical storage structure of the database, which brings convenience to the organization and use of the database. Different users can have their own data views, and the data views of all users are concentrated in Unify the organization together to get a global data view.

Use storage description language to define and describe global data view data, and store the data on physical media.

There are two mappings:

One is the mapping between the external schema and the conceptual schema, which defines the correspondence between them and ensures the logical independence of the data;

The other time is the mapping between the conceptual schema and the internal schema, which defines the correspondence between the logical structure of the data and physical storage, making the global logical data independent of the physical storage and ensuring the physical independence of the data.

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