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

ER DIAGRAM, NEED ER DIAGRAM WITH MINIMUM ENTITY AND RELATIONSHIP of Hospita...

NEED ER DIAGRAM WITH MINIMUM ENTITY AND RELATIONSHIP of Hospital Management System

Mixed fragmentation, Mixed fragmentation: Sometimes, horizontal fragmentati...

Mixed fragmentation: Sometimes, horizontal fragmentation or vertical fragmentation of a database schema by itself is insufficient to sufficiently distribute the data for some appli

Assignment SQL Management Server 2012, Have database built but having probl...

Have database built but having problems with some questions that go with the database

What is the full form of odbc, What is the full form of ODBC ? ODBC stand...

What is the full form of ODBC ? ODBC stands for Open Database Connectivity.

Write short notes on relational model, Write short notes on relational mode...

Write short notes on relational model   The  relational  model  uses a  collection of  tables  to show  both data  and the relationships between those  data.  The relational mo

File manager-database management system, File Manager File manager ha...

File Manager File manager handles the allocation of space on disk storage. It starts and maintains the list of structures and indices described in the internal schema that is

Databases and data warehouses , Databases and data warehouses both are data...

Databases and data warehouses both are databases and both contains number of rows and columns of tables containing data. Data warehouse is really different from databases because d

Dataset, The dataset " CFOLYMPICS.XLS " contains the observations used in t...

The dataset " CFOLYMPICS.XLS " contains the observations used in the above article.  The definitions of the variables are also included in this spreadsheet.  However, for the purpo

Define the immediate update, Define the Immediate Update The immediate...

Define the Immediate Update The immediate update methods may apply changes to the database on disk before the transaction arrives a successful conclusion. Though, these change

Can you delete data element, Can we delete data element, which is being use...

Can we delete data element, which is being used by table fields. No we cant delete data element.

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