Explain saving derived attributes to avoid re-computation, Database Management System

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

Posted Date: 8/30/2013 5:17:18 AM | Location : United States







Related Discussions:- Explain saving derived attributes to avoid re-computation, Assignment Help, Ask Question on Explain saving derived attributes to avoid re-computation, Get Answer, Expert's Help, Explain saving derived attributes to avoid re-computation Discussions

Write discussion on Explain saving derived attributes to avoid re-computation
Your posts are moderated
Related Questions
Describe the Composite Key Composite Key: Sometimes one key is not enough to uniquely recognize a row. E.g. in a single class Roll is enough to search a student, but in the w

It can be easily defined as: The database must not have any unmatched foreign key values. The term "unmatched foreign key value" means a foreign key value for which there doe


Transactions And Concurrency Management  Introduction One of the main benefits of storing data in an integrated repository or a database is to permit sharing of it betwee

Question: (a) Use the following business rules to produce the E-R diagram. You should clearly show all the minimum and maximum cardinality constraint on each side of the relati

Partial Key : It is a group of attributes that can uniquely identify small entities and that are related to same base entity. It is sometime named as Discriminator.  Altern

Safe Banking is a Canberra based credit union, which has several branches around Canberra and Queanbeyan. YOU have taken over Safe Banking. YOU need to create a database that organ

It defines that the tuple in one relation that refers to another relation must refer to an existing tuple in that relation. This constraint is states on two relations (not essentia

Develop Database academic assignment Project Description: For a provided set of instructions in a case study design Entity Relationship Diagram. - Entity Relationship Diag

Define Deadlock recovery measures                   To recover from deadlock, the cycle in the wait-for-graph should be broken. The common technique of doing this is to rollbac