A key goal during this stage is data independence, meaning that the decisions made for performance optimization purposes should be invisible to end-users and applications.
12.
Logical data independence is more difficult to achieve than physical data independence, since application programs are heavily dependent on the logical structure of the data that they access.
13.
Logical data independence is more difficult to achieve than physical data independence, since application programs are heavily dependent on the logical structure of the data that they access.
14.
The three-level database architecture relates to the concept of " data independence " which was one of the major initial driving forces of the relational model.
15.
"' Data independence "'is the type of data transparency that matters for a centralised applications to changes made in the definition and organization of data.
16.
While many systems built on SQL fail miserably with respect to Codd's rule 9 " Logical data independence ", Dataphor applications can automatically change when the logical layer change.
17.
Physical data independence is present in most databases and file environment in which hardware storage of encoding, exact location of data on disk, merging of records, so on this are hidden from user.
18.
No mainstream DBMS systems are fully based on it ( they tend not to exhibit full physical independence or to prevent direct user access to the conceptual level ), but the idea of logical data independence is widely adopted.
