Vertical fragmentation, Database Management System

Assignment Help:

Vertical Fragmentation-Vertical fragmentation groups together only those attributes in a relation that are used jointly by various important transactions. A vertical fragment is described using the Projection operation of the relational algebra. In its most easy form, vertical fragmentation is the similar as that of decomposition. In common, a relation can be constructed on taking Natural join of all vertical fragments.

More usually, vertical fragmentation is accomplished by adding a special attribute known as a tuple-number to the scheme R. A tuple-number is a logical or physical address for a tuple. Therefore every tuple in R must have a unique address, the tuple- number attribute is a key to the new fragments get (please refer to Figure ).

Branch-code

Account number

Customer name

Balance

Tuple-number

1101

3050

Suresh

5000

1

1101

2260

Swami

3360

2

1102

1170

Swami

2050

3

1102

4020

Khan

10000

4

1101

1550

Khan

620

5

1102

4080

Khan

1123

6

1102

6390

Khan

7500

7

                                      Figure: The relation DEPOSIT of figure 5 with tuple- numbers

This  relation  now  can  be  decayed  into  two  fragments  as:  demonstrates  a  vertical decomposition of the scheme Deposit-scheme tuple number into:

DEPOSIT3 =  (branch-code. customer-name, tuple-number) (DEPOSIT)

DEPOSIT4 = ∏  (account-number, balance, tuple-number) (DEPOSIT)

The example of above Figure on this basis would become:

DEPOSIT3

Branch-code

Customer-name

Tuple-number

1101

Suresh

1

1101

Swami

2

1102

Swami

3

1102

Khan

4

1101

Khan

5

1102

Khan

6

1102

Khan

7

DEPOSIT4

Account number

Balance

Tuple-number

3050

5000

1

2260

3360

2

1170

2050

3

4020

10000

4

1550

620

5

4080

1123

6

6390

7500

7

                                                     Figure: Vertical fragmentation of relation DEPOSIT

How can we rebuild the original relation from these 2 fragments? By taking natural join of the 2 vertical fragments on tuple-number. The tuple number permits direct retrieval of the tuples without the required for an index. Therefore, this natural join may be computed much extra efficiently than typical natural join.Though, please note that as the tuple numbers are system generated, thus they should not be visible to common users. If users are given access to tuple-number, it happens to impossible for the system to change tuple addresses.

 


Related Discussions:- Vertical fragmentation

Describe second normal and third normal form, Database Management Systems ...

Database Management Systems 1. Explain SQL Server 2000 Architecture with diagram. 2. Describe Second Normal and Third Normal Form. 3. Explain about query engine and stora

What is system r?what are its two major subsystems?, System R was develop...

System R was developed and designed over a period of 1974-79 at IBM San Jose Research Company. Its purpose was to illustrate that it is possible to create a Relational System tha

What is the role of order by clause, What is the role of ORDER By Clause? ...

What is the role of ORDER By Clause? ORDER BY clause: The ORDER BY clause permits you to sort the records in your result set. The ORDER BY clause can just be used in select s

Describe the grant function and explain security, Describe the GRANT functi...

Describe the GRANT function and explain, how it associates to security. What kind of privileges may be granted? How are they revoked? Ans: Since more than one user can aacce

ERD DIAGRAM, Law Associates is a large legal practice based in Sydney. You...

Law Associates is a large legal practice based in Sydney. You have been asked to design a data model for the practice based upon the following specification: The practice employs

#title., losers with new information systems

losers with new information systems

Keys - relational database integrity, Candidate Key:  In a relation R, a ca...

Candidate Key:  In a relation R, a candidate key for R is a subset of the set of attributes of R, which have the differnt two properties: (1)        Uniqueness:                N

Write short notes on index structure of files, WRITE SHORT NOTES ON INDEX S...

WRITE SHORT NOTES ON INDEX STRUCTURE OF FILES? There are two basic parts of indices 1.   Ordered indices 2.   Hash indices Every technique must be evaluated on the bas

Explain concept of inheritance with support of example, Explain concept of ...

Explain concept of inheritance with support of suitable example. Inheritance Inheritance is one of milestone of object-oriented programming language as it allows a creati

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