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

Develop and evaluate partial systems, Part 1: Security Plan Consider th...

Part 1: Security Plan Consider the Case study and identify 3 security requirements. For each of these security requirements: • Discuss the necessity for the feature and how

What is a records management consultation, What is a records management con...

What is a records management consultation? Our organization is an authority for disseminating your specific requirements and giving you with a solution to effectively manage yo

Describe log based recovery, Describe log based recovery The most usabl...

Describe log based recovery The most usably structure for recording data base modification is the LOG the log is a sequence of log records recording all the update activities i

Explain the fundamental concepts of object-orientation, Explain the Fundame...

Explain the Fundamental concepts of object-orientation Software developers, data base administrators (DBAs) need to be familiar with fundamental concepts of object-orientation.

What is called an evaluation primitive, What is called an evaluation primit...

What is called an evaluation primitive? A relational algebra operation annotated with instructions on how to evaluate is known as an evaluation primitive.

What is oom, What is OOM? Object oriented modeling is an approach by wh...

What is OOM? Object oriented modeling is an approach by which modeling of systems is done by visualizing the system based on real world concepts. Object oriented modeling does

What are the various properties of relational tables, What are the various ...

What are the various properties of Relational tables? Relational tables have 6 properties: 1. Each row is unique. 2. Column values are of the same kind. 3. Values are

Explain th process to avoid re-computation, Saving Derived Attributes to Av...

Saving Derived Attributes to Avoid Re-computation Data that is derived from other data should be stored in the computed form to avoid re-computation. For this, we could define

Write short notes on tuple relational calculus, Write short notes on tuple ...

Write short notes on tuple relational calculus. The tuple relational calculation is anon procedural query language. It defines the desired information without giving a particul

Define sequence, Define Sequence A sequence is a set of integers 1, 2, ...

Define Sequence A sequence is a set of integers 1, 2, 3 that are generated in order on demand. Sequences are regularly used in databases because lots of applications require ev

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