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

Represent the form as a relational schema, Question: This form represen...

Question: This form represents one of a number used for each sailing of a range of boats. A passenger may go on many sailings and will have the same passenger number for each.

In oracle what is system global area and how is it organized, In Oracle wha...

In Oracle what is system global area and how is it organized? The SGA is a collection of shared memory fields which along with the Oracle processes constitute an Oracle instan

Convert erd to rdm model, Regional Gardens has many nurseries, including Wa...

Regional Gardens has many nurseries, including Wagga Wagga, Bathurst, Albury, Orange, and Dubbo. Each nursery is known by its campus code, eg WW, B, A, O and D respectively. Additi

Exclusive lock, Exclusive lock It is asked for by a transaction on...

Exclusive lock It is asked for by a transaction on a data item that it wants to update. No other transaction can put either a shared lock or an exclusive lock on a dat

Give two profit of reuse of code, Give two profit of Reuse of Code. Re...

Give two profit of Reuse of Code. Reusing the implementation . Place existing class directly inside a new class. The new class can be made up of any number and type of the oth

Functional Dependencies, What exactly is the concept of Functional Dependen...

What exactly is the concept of Functional Dependencies? And how do we associate this concept with the logic of Super-keys, Candidate Keys, etc? Given Relation R(A,B,C,D,E) with de

Create a technology web server, Database design Database tables will be...

Database design Database tables will be created for you on the Technology web server. The schema will be as follows. Please note that this is a simplified database structure, d

ER diagram, #question. acompani datdbase needs to store information about e...

#question. acompani datdbase needs to store information about employees (identified by a social security number,with salary and phone as attributes) and departments (identified by

What is object containment, What is object containment? References amon...

What is object containment? References among objects can be used to model dissimilar real-world concepts.

State about the use case diagram, State about the Use Case Diagram A u...

State about the Use Case Diagram A use case diagram represents a set of use cases, actors and their relationships. These diagrams shall be used to model context or requirement

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