Logical and Physical Data Independence

Synonyms

Database schema; DBMS

Definition

These concepts were developed to separate the database schema that the users and programmers see from the storage details and indexing methods of the database and are best explained using the database architecture known as the three-schema architecture. This architecture assumes that there are database schemas or descriptions at three levels: (1) the user view level, which describes a portion of the database for a particular class of users; (2) the conceptual schema, which describes a whole database in a representational data model such as the relational model or the object model; and (3) the internal schema, which describes the storage structures and indexing methods that describe the database files. Physical data independence is defined as the capability to change the internal schema (storage structures/indexes) without having to change the conceptual schema. Logical database independence is defined as the capability to change the conceptual...