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GATE 2020 : Database Quiz 3

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Question 1

Consider the following relation schemas.
Suppliers(sid,sname,address)
Parts(pid,pname,color)
Catalog(sid,pid,cost)
Write relational algebra query to find the names of suppliers who supply some red part.

Question 2

The natural join is a binary operation, it allows us to combine certain selections and Cartesian product into one operation. Then which of the following is true for natural join

Question 3

If P and Q are predicates and e is the relational algebra expression, then which of the following equivalence are valid?

Question 4

Let R and S be two relations with the following schema
R(P, Q, R1, R2, R3)
S (P, Q, S1, S2)
where {P, Q} is the key for both schemas. Which of the following queries are equivalent?
I.
II.
III.
IV.

Question 5

Consider a join (relation algebra) between relations r(R)and s(S) using the nested loop method. There are 3 buffers each of size equal to disk block size, out of which one buffer is reserved for intermediate results. Assuming size (r(R)) < size (s(S)), the join will have fewer number of disk block accesses if

Question 6

Consider a database that has the relation schema CR (StudentName, CourseName). An instance of the schema CR is as given below.

The following query is made on the database.

The number of rows in T2 is _____.

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GATE & PSU CS Databases

Jun 25GATE & PSU CS