DBMS Data Independence

A major objective for the three-level architecture is to provide data independence, which means that upper levels are unaffected by changes to lower levels. There are two kinds of data independence: logical and physical.

Logical Data Independence

Logical data independence can be defined as the immunity of the external schemas to changes in the conceptual schema.

Physical data independence

Physical data independence can be defined as the immunity of the conceptual schema to changes in the internal schema.