data independence


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data independence

[′dad·ə in·də′pen·dəns]
(computer science)
Separation of data from processing, either so that changes in the size or format of the data elements require no change in the computer programs processing them or so that these changes can be made automatically by the database management system.

data independence

Techniques that allow data to be changed without affecting the applications that process it. There are two kinds of data independence. The first type is data independence for data, which is accomplished in a database management system (DBMS). It allows the database to be structurally changed without affecting most existing programs. Programs access data in a DBMS by field and are concerned with only the data fields they use, not the format of the complete record. Thus, when the record layout is updated (fields added, deleted or changed in size), the only programs that must be changed are those that use those new fields.

Data Independence for Processing
The second type of data independence relates to processing and refers to miscellaneous data used in programs that might change in the future, such as discount rates, product descriptions and error messages. Such data should be stored in a database and not "hard wired" into the code of the program. When values change, only the database item is altered, a much simpler task than recompiling numerous programs.


Data Independence for Data
Program #1 reserves space for the entire record (fields A to K). If the record format is changed, the space must be changed. Program #2 calls the DBMS to deliver just the fields it uses (D G H K). It still reserves space, but unless a field has been resized, it is not affected by other field changes. Program #3 is fully independent of the data structure. It calls for data by field name, and the DBMS allocates the space at runtime.







Data Independence for Processing
Program #1 uses a hard-coded value to test credit limit. To change the limit, the program must be recompiled. Program #2 retrieves the credit limit from a database. To change it, only the database must be updated, a simpler task.
References in periodicals archive ?
Following is the full text of Jigsaw's "Declaration of Data Independence.
The Pig project at Yahoo [10] and the SCOPE project at Microsoft [11] aim to integrate declarative query constructs from the database community into MapReduce-like software to allow greater data independence, code reusability, and automatic query optimization.
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Data independence is a set of networking considerations which segregates data by purpose and by utilization.
Leading the Charge for the Democratization of Data, Jigsaw Declares June 4, 2008 Data Independence Day and Makes Company Data Freely Accessible.
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Tamino protects data independence by following an open database management system philosophy, providing interfaces such as DCOM, ODBC and JDBC.
Not only does our product's unique data independence provide users with a fast, efficient development platform, but it allows management to maintain their existing databases, including legacy systems.
developer and marketer of application development platforms based on data independence, has acquired Pittsburgh-based OPSoft Technologies to develop a channel sales group for marketing the Cerebellum(TM) product through strategic partnerships.
developer and marketer of application development platforms based on data independence, today announced that it will kick off a free national seminar series, called "Any Luck Playing Connect-the-Data?
XML adds the power of data independence, enabling you to easily exchange data between non-compatible systems.
With its use of Java(TM) technology and CORBA's open standards, Cerebellum extends platform and operating system independence to data independence by treating all data sources as though they were from the same vendor and by generating the necessary code for communicating with the underlying data systems.