BARC CS 2018 Nuclear Quiz -1 ( DBMS )
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Question 1
After transforming the above ER diagram into its relational model the following two relations were identified
PERSON (EMPNO#, NAME, ADDRESS)
CONTRACT EMPLOYEE (EMPNO#, NAME, ADDRESS ,CONTRACT PERIOD)
FOREIGN KEY:(EMPNO#REFERNCES, PERSON)
Select from among the following the changes which are required/ possible for the above two relations
1) CONTRACT PERIOD attribute should be included in the person relation
2) NAME and ADDRESS attributes should be eliminated from the CONTRACT EMPLOYEE RELATION
3) It is necessary to have two relations called PERSON and CONTRACT EMPLOYEE to represent the diagram but one relation is enough
Question 2
Question 3
How many tuples are there in relation(Natural join) R1
R2?Question 4
Question 5
In a database system, unique time stamps are assigned to each transaction using Lamport’s logical clock. Let TS(T1) and TS(T2) be the timestamps of transactions T1 and T2 respectively. Besides, T1 holds a lock on the resource R, and T2 has requested a conflicting lock on the same resource R. The following algorithm is used to prevent deadlocks in the database system assuming that a killed transaction is restarted with the same timestamp.
if TS(T2) < TS(T1) then
T1 is killed
else T2 waits.
Assume any transactions that is not killed terminates eventually. Which of the following is TRUE about the database system that uses the above algorithm to prevent deadlocks?
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GATE & PSU CSDatabases
