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

What is the use of keyword isa, What is the use of keyword ISA? The use...

What is the use of keyword ISA? The use of keyword ISA is to show that a class is a specialization of another class.

What features relational dbms contribute level of integrity, A well-maintai...

A well-maintained relational DBMS has a high level of data integrity. What features of a relational DBMS contribute towards this level of integrity? Relational DBMS gives high

Entity relationship diagram, Ask questApollo Hospitals (AH) is a popular me...

Ask questApollo Hospitals (AH) is a popular medical service provider in Oman. AH wants to automate its business functions into an information system. The proposed information syst

Case snerio, each publisher has uniqe name a mial addrs are also kept on ea...

each publisher has uniqe name a mial addrs are also kept on each pubisher.a publisher publish one book.a book publish y one publisher.book identified by isbn.each book writn by one

Apriori algorithm-find all frequent large itemsets, Your friend owns a comp...

Your friend owns a computer store in Yuen Long, selling Desktop and Notebook PCs and other computer peripherals. Having been rather successful with his business there, he decided t

Define the two phase locking protocol, Define the Two Phase Locking Protoco...

Define the Two Phase Locking Protocol This is a protocol that is used to make sure serializability of transactions. This protocol needs that every transaction issue lock and u

relationship with the owner entity, A database for the Service and Mainten...

A database for the Service and Maintenance (SM) section of a Computer sales and service Company has to be developed. SM gives after sales service to customers. SM branch has a numb

Describe data manipulation language, Describe Data Manipulation language ? ...

Describe Data Manipulation language ? Data Manipulation Language (DML) - A data manipulation language is a language which enables users to access or manipulate data as organize

MS Access 2010 - Form Updates Table, Hi there, Have an issue with my Databa...

Hi there, Have an issue with my Database. I have: TblOrderDetails and FmOrderDetails TblCircuit and FmCircuit Whenever I add data into the Form, it will update the table as expect

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