Explain saving derived attributes to avoid re-computation, Database Management System

Assignment Help:

Saving Derived Attributes to Avoid Re-computation  

As discussed, "redundancy means duplication of exact data". But, if multiple copies of same data are present in the system, then it can increase chance of availability of data, but the problem of computing overhead is also associated with it.

To overcome this difficulty we can "cache" or store the redundant data in its computed form and classes or objects might be defined to retain this information. The class which contains cached data must be updated if any of objects that it depends on are changed.

Figure shows use of derived object and derived attribute in OMTool. Each class box contains an ordered list of operations and attributes, each represented as text string (left of diagram). Given the location of the class box itself, the location of each attribute can be computed by adding up the size of all the elements in front of it. Since location of each element is required frequently, location of each attribute string is computed and then stored. The region containing entire attribute list is also computed and saved. In this way, you can avoid the testing of input points against the attribute text element. It is shown in the right side in Figures. If a new attribute string is added to list, then locations of the ones after it in list are simply offset by size of the new element.

 

728_Derived attribute to avoid re-computation.png

                                                                       Figure: Derived attribute to avoid re-computation


Related Discussions:- Explain saving derived attributes to avoid re-computation

Explain the concept of data mining, Question 1 Explain the concept of Fore...

Question 1 Explain the concept of Foreign Key. How a foreign key differs from a Primary Key? Can the Foreign Key accept nulls? Question 2 With a necessary example explain (i)

Define direct file organization, Define Direct file organization? The d...

Define Direct file organization? The direct file organization is employed to enhance the performance in accessing the records than sequential file organization. In direct file

What is index, What is Index? An index is a physical structure having p...

What is Index? An index is a physical structure having pointers to the data. Indices are created in an existing table to locate rows more quickly and efficiently. It is possibl

What is the use of group by clause, What is the use of group by clause? ...

What is the use of group by clause? Group by clause is used to be relevant aggregate functions to a set of tuples. The attributes given in the group by clause are used to shape

What database management system, Company XYZ is an advertising company. It...

Company XYZ is an advertising company. It has its own website but the search facilities offered are not reliable. The company is willing to invest to acquire new machines and sof

Determine the steps of path in association network, Determine the steps of ...

Determine the steps of path in association network You can analyse use of paths in association network in the following steps:  Examine every operation and see what asso

Define the terms entity, Define the terms entity, attribute, role and relat...

Define the terms entity, attribute, role and relationship between the entities, giving examples for each of them.         Ans: Entity:   An entity is a "thing" or "object" in th

Pl/SQL, I need solution of the question posted at http://www.expertsmind.c...

I need solution of the question posted at http://www.expertsmind.com/questions/sql-query-for-testing-triggers-and-stored-procedures-30140149.aspx

State the functional approach of object oriented methods, State the functio...

State the functional approach of object oriented methods Moving from a functional approach to an object oriented one needs a translation of functional model elements into objec

Need for distributed database systems, Need For Distributed Database System...

Need For Distributed Database Systems A distributed database is a set of database kept on multiple computers that appears to applications as a one database. As a result, an app

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