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(a) Design a query plan for the following distributed query: An application at site B wants to compute a join of STUDENT ?Id=StudId TRANSCRIPT where STUDENT (Id,Major) is at site B and TRANSCRIPT (StudId, CrsCode) is at site C. The result should be returned to B. Assume that semijoin is not used. Also assume that
(b) Estimate the cost of computing σMajor='CS' (STUDENT) ?Id = StudId TRANSCRIPT using the semijoin strategy. Use the sizes of the STUDENT and TRANSCRIPT relations and of their attributes from the part (a) above. In addition, assume that 10% of the students major in CS. Compare this with the solutions in part (a) above that do not use the semijoin.
Define Forms Based Interfaces? Forms-Based Interfaces - A forms-based interface display a form to each user. Forms are commonly designed and programmed for naive users and inte
Define the terms i) Entity type ii) Entity set Entity type: An entity type describes a collection of entities that have the similar attributes. Entity set: The set of all en
Farmer Bob, Farmer Jane and Farmer Jose run a cow farming co-op. For every cow they keep the cow’s name, age (or date of birth), breed and numbered plastic ear tag. The each of t
About Attribute inheritance
management information system based on functional organisation
State the Component Diagram A component diagram represents a set of component and relationships among them. In a dynamic model, component diagram is used to model physical com
Set Difference If R1 and R2 are two union compatible relations or relations then result of R3 =R1- R2 is the relation that have only those tuples that are in R1 but not in R2.
In case of entity integrity, the primary key may be declared? In a case of entity integrity primary key may be not Null.
Multiple-mode locks : It offers two locks: exclusive locks and shared locks. But why do we require these two locks? There are a lot of transactions in the database system that neve
The indices are accumulated in the index files. The data is accumulated in the data files. Indices give fast access to data items. For example, a book database may be managed in th
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