Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
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.
Figure: Derived attribute to avoid re-computation
Update Operations and Dealing with Constraint Violations There are three basic operations to be executes on relations: Insertion Deletion Update The INSER
What are the two types of serializability? The two types of serializability is a) Conflict serializability b) View serializability
Need for Client Server Computing- Client/Server (C/S) architecture includes running the application on multiple machines in which every machine with its component software tackles
Give a sample of the Dynamic Model. The sample of dynamic model is given below: Dynamic model for the car: Brake and Accelerator Brake or Applies Accelerator
I need help for my Uni assignments
Create centralized relational database using Top down method- Construction of Logical Model: Translation EERD into Relational Schema: Use the 8 steps algorithm of converting EERD
DROP TABLE Command: When an existing object is not needed for further use, it is always better to eliminate it from the database. To remove the existing object from the databas
What is meant by functional dependencies? Consider a relation schema R and α C R and β C R. The functional dependency α ->β holds on relational schema R if in any legal relati
Question: Using the data model express the following queries in SQL. (a) Create the Table named "Cinema" and make the cinema_code to be the primary key of the relation and
The data of a view is not physically stored, but derived from one or more tables. True the data of a view is not physically stored
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!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd