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

Sql insert statements, Submit SQL INSERT Statements that will populate the ...

Submit SQL INSERT Statements that will populate the database with sample data.  You must insert at least 5 records into each table in your database.Submit your SQL INSERT Statement

Assignment - 1 - redoing to improve grades, Assignment #1 Data Management ...

Assignment #1 Data Management The questions on this exam are based on the Baxter Aviation case scenario. 1. (5 points) The systems analyst proposes the following two relationshi

Hashed file organisation, Hashed File Organisation Hashing is the most ...

Hashed File Organisation Hashing is the most common form of purely random access to a database or file. It is also used to access columns that do not have an index as an optimi

Hass, waht is a repeating group?

waht is a repeating group?

Explain query execution plan, Explain query execution plan? - Optimizer...

Explain query execution plan? - Optimizer available in SQL Server optimizes code to be effectively executed. - A query execution plan demonstrates how this optimizer would r

User error-database errors, User error :  This contains errors in the progr...

User error :  This contains errors in the program (e.g., Logical errors) with errors made by online users of database.  These types of errors can be avoided by applying some check

State the process of rearranging classes and operations, State the process ...

State the process of Rearranging Classes and Operations The various, yet similar operation of different classes can be slightly modified thus that they can be covered by a sin

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

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