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

What are the ways of obtaining the connection parameters, What are the ways...

What are the ways of obtaining the connection parameters?  Hardwire the parameters into the program. Ask for the parameters interactively. Get the parameters

Describe the most important classes of parallel machines, Question 1 Discu...

Question 1 Discuss the classification of DBMS based on location of database Question 2 Explain with examples different SQL commands used for creating and deleting relations.

Describe the terms ‘database'' and ‘data warehouse'', Problem: ‘Users a...

Problem: ‘Users and Information system specialists need to spend inordinate amounts of time locating and gathering data' (Watson and Hal, 1998) Recent developments in the ar

Explain the dependency relationship of object oriented, Explain the depende...

Explain the dependency relationship of object oriented A dependency is a relationship which states that a change in specification of one thing can affect another thing, but n

What are the kinds of strings, What are the kinds of Strings?  -A binar...

What are the kinds of Strings?  -A binary string in MySQL is one that MySQL treats as case sensitive in comparisons. -A non binary string in MySQL is one that MySQL does'nt

System level permissions-data control, System level permissions : With the ...

System level permissions : With the use of data dictionary you can view them.       Let us take the table name as user_sys_privs (used in oracle).       DESCRIBE USER_SYS_PRI

What is the disadvantage of a call by reference, What is the disadvantage o...

What is the disadvantage of a call by reference? During a call by reference damage or loss of data is not restricted to the subroutine, but will instantly lead to alters to th

What is substitutability, What is substitutability? Any method of a cla...

What is substitutability? Any method of a class-say A can equally well be adjured with any object belonging to any subclasses B of A. This characteristic leads to code reuse, a

Non-redundant cover and canonical cover, Given the following set of functio...

Given the following set of functional dependencies {cf?bg, g?d, cdg?f, b?de, d?c} defined on R(b,c,d,e,f,g) a.Find a non-redundant cover. b.Find a canonical cover.

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