Security-data fragmentation, Database Management System

Assignment Help:

Security: Data not needed by local applications is not stored at the site, therefore no unnecessary security violations may exist.

But how can we carry out fragmentation? Fragmentation may be carried out as per the following rules:

a)      Completeness: This rule makes sure that there is no loss of data while fragmentation. If a relation is decomposed into fragments, then every data item must appear in at least single fragment.

b)      Reconstruction: This rule makes sure preservation of functional dependencies. It should be possible to describe a relational operation that will reconstruct the relation from its fragments.

c)       Disjointness: A data item that shows in a fragment should not show in any other fragment. Though, a typical fragmentation known as vertical fragmentation is an exception to this rule. In vertical fragmentation the primary key attributes must be repeated to permit reconstruction of original relation.

This rule makes sure minimization of data redundancy. What are the dissimilar types of fragmentation?

 


Related Discussions:- Security-data fragmentation

Distinguish among different kinds of parameters, How can one distinguish am...

How can one distinguish among different kinds of parameters? Input parameters are used to pass data to subroutines. Output parameters are used to pass data from subrout

Explain different addressing modes of 8086, 1. Explain different addressing...

1. Explain different addressing modes of 8086 Explanation of all addressing modes 2. Write a sequence of instructions to exchange two register contents using stack

What are referential integrity constraints, What are referential integrity ...

What are referential integrity constraints? A value that appears in single relation for a given set of attributes also appears for a particular set of attributes in another rel

Alter table command, ALTER TABLE Command : This command is used for variati...

ALTER TABLE Command : This command is used for variation of existing structure of the table in the given situation: When a new column is to be added to the table structure.

Define the one-way associations, One-way Associations When an associat...

One-way Associations When an association is traversed only in the one direction, then it is implemented as a pointer i.e.an attribute which contains an object reference. If mu

Draw an e-r diagram and convert it to a relational schema, In an organisati...

In an organisation various projects are undertaken. Each projects can employ one or more employees. Every employee can work on one or more projects. Each project is undertaken on

What is inheritance, What is inheritance? Define it in detail?  Inheri...

What is inheritance? Define it in detail?  Inheritance Inheritance can be at the levels of types, or at the level of tables we first consider inheritance of types, then i

What is a hashing function, What is a hashing function?  What are the prope...

What is a hashing function?  What are the properties of a good hashing function?  Describe the folding technique for hashing functions.      Ans:  Hashing function is a method

Where does view definition stored, Where does view definition stored? ...

Where does view definition stored? A view definition is permanently stored as part of the database.

Define partial, Partial Key : It is a group of attributes that can uniquel...

Partial Key : It is a group of attributes that can uniquely identify small entities and that are related to same base entity. It is sometime named as Discriminator.  Altern

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd