Vertical fragmentation, Database Management System

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.

 

Posted Date: 3/13/2013 8:41:23 AM | Location : United States







Related Discussions:- Vertical fragmentation, Assignment Help, Ask Question on Vertical fragmentation, Get Answer, Expert's Help, Vertical fragmentation Discussions

Write discussion on Vertical fragmentation
Your posts are moderated
Related Questions
All edges of a cube are expanding at a rate of 6 centimeters per second. How fast is the surface area changing when each edge is (a) 2 centimeters and (b) 10 centimeters?

Create role named role_table that allows a user to create tables. Using role_table allow users kripa and reena to create tables. CREATE ROLE role_table; GRANT CREATE ANY TABLE

Describe queries with complex types? The present extension of the SQL query language deal with the complex type Let us start with the simple example: Find the title and t

What is a Transaction? A transaction is an event which happens on the database. Generally a transaction reads a value from the database or writes a value to the database. If y

Making Common Behaviour Abstract Let us define abstraction "Abstraction means to focus on the necessary, inherent aspects of an entity and ignoring its accidental features". O

I want to fragment existing table using java code... help me..!!

In case of entity integrity, the primary key may be declared? In a case of entity integrity primary key may be not Null.

The aims of the project are: 1. To enable the students to undertake the detailed design of a specific plant or process 2. The design projects includes: process selection; und

ADVANCE OBJECT DESIGN Introduction Analysis is the initial step of the OMT methodology. It is apprehensive with devising a precise, concise, correct and understandable mo

What is meant by mean time to failure? The mean time to failure is the amount of time that the system could run continuously without failure.