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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.
Describe Hashing in DBMS? Hashing: Hashing is a technique to store data within an array so which storing, searching, inserting and deleting data is fast (in theory it's O(1))
Explain the main advantages of DBMS over File Oriented System ?
The participation Constraints shows whether the existence of an entity depends on its being associated to another entity by the relationship type. There are two kinds of participat
An important first step to the statistical analysis of data is to "get to know your data". The following tasks should contribute to this. (a) To the right of the dataset cons
#question.explain diversity and magnitude of organic compounds and general properties?
Write a program within embedded SQL to associative the total trip expenses of the salesman named ‘John' for the relations. EXEC SQL BEGIN DECLARE SECTION; long total_expenses;
Define the Boyce-Codd Normal Form with instance and also Compare BCNF and 3NF. Ans: BCNF: For each functional dependency X->Y in a set F of functional dependencies over relati
What are the problems if one were not to normalize? When do these problems surface? Ans: Database normalization, sometimes considered to as canonical synthesis, is
Explain the structure of well formed formulae in relational calculus. Ans: a. An atom is a formula b. If P1 is a formula, after that so are ¬P1 and (P1) c. If P1 and P2 a
It defines that no primary key value can be null. This is as the primary key is used to recognize individual tuple in the relation. So we will not be able to recognize the records
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