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

Entity relationship, how to write tables and drow E-R diagrams for hosiptal...

how to write tables and drow E-R diagrams for hosiptal management system and how to normalize and cardinalities?

Benefits of views-data control, Benefits: It limits data access. ...

Benefits: It limits data access. It makes difficult queries look easy. It permits data independence. It presents dissimilar views of the similar data.

Explain projection operation distribute over union operation, Illustrate th...

Illustrate the statement 'Projection operation distributes over the union operation'. Give an example.    Ans: Π L (E 1 ∪ E 2 ) = (Π L (E 1 )) ∪ (Π L (E 2 ))   This says th

Increased parallelism-data replication, Increased parallelism : Since the r...

Increased parallelism : Since the replicated date has several copies a query can be distributed or can be answered from the smallest loaded site. Also, with more replicas you have

Conflicting operations in schedule, Conflicting Operations in Schedule: ...

Conflicting Operations in Schedule: The three simple ways of interleaved instruction implement of transactions T1 and T2. Please note that in the following tables the first col

Design and building a distributed information system, The scenario You ...

The scenario You have been approached to design and implement a prototype of a distributed information system for a national car part retail outlet chain. The company comprises

Demonstrate the uml model, Demonstrate the UML model Using UML, it is p...

Demonstrate the UML model Using UML, it is possible to generate code in any of the programming language from UML model (called forward engineering) and rebuild a model from an

File organization, what is file organization? what are file organization te...

what is file organization? what are file organization techniques.explain in detail? explain random file organization technique, multikey file organization technique?what is indexin

Data handling and research methods, Data Handling and Research Methods: ...

Data Handling and Research Methods: The dataset encompassing 130 participants contains several variables measuring detrimental health related behaviours referring to the use o

Advantages of Observation Methods, Advantages of Observation  Methods: ...

Advantages of Observation  Methods: Bailey has pointed  out four  advantages of observation: 1. Superior in Data  Collection  on Non Verbal Behavior: When  a person  a opi

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