DBMS |Gate-2016| Previous Year Questions| Set-5

Set-15 GATE-2006 DBMS

DBMS |Gate-2016| Database Management System

1. Which of the following is NOT a superkey in a relational schema with attributes V, W, X, Y, Z and primary key VY? [GATE – 2016]

a. VXYZ
b. VWXZ
c. VWXY
d. VWXYZ

Answer : b)


2. NOT a part of the ACID properties of database transactions? [GATE – 2016]

a. Atomicity
b. Isolation
c. Consistency
d. Deadlock-freedom

Answer : d)


3. A database of research articles in a journal uses the following schema.

(VOLUME, NUMBER, STARTPAGE, ENDPAGE, TITLE, YEAR, PRICE)

The primary key is (VOLUME, NUMBER, STARTPAGE, ENDPAGE) and the following functional dependencies exist in the schema.

(VOLUME, NUMBER, STARTPAGE, ENDPAGE) → TITLE
(VOLUME, NUMBER) → YEAR
(VOLUME, NUMBER, STARTPAGE, ENDPAGE) → PRICE

The database is redesigned to use the following schemas.

(VOLUME, NUMBER, STARTPAGE, ENDPAGE, TITLE, PRICE)
(VOLUME, NUMBER, YEAR)

Which is the weakest normal form that the new database satisfies, but the old one does not? [GATE – 2016]

a. 1NF
b. 2NF
c. BCNF
d. 3NF

Answer : b)


4. Consider the following two phase locking protocol. Suppose a transaction T accesses (for read or write operations), a certain set of objects{O1,…,Ok}. This is done in the following manner:

Step1. T acquires exclusive locks to O1,…,Ok in increasing order of their addresses.
Step2. The required operations are performed.
Step3. All locks are released.

This protocol will : [GATE – 2016]

a. guarantee serializability and deadlock-freedom
b. guarantee neither serializability nor deadlock-freedom
c. guarantee serializability but not deadlock-freedom
d. guarantee deadlock-freedom but not serializability

Answer : a)


5. B+ Trees are considered BALANCED because: [GATE – 2016]

a. the lengths of the paths from the root to all leaf nodes are all equal.
b. the lengths of the paths from the root to all leaf nodes differ from each other by at most 1
c. the number of children of any two non-leaf sibling nodes differ by at most 1.
d. the number of records in any two leaf nodes differ by at most 1.

Answer : a)
DBMS |Gate-2016|


6. Suppose a database schedule S involves transactions T1, …, Tn. Construct the precedence graph of S with vertices representing the transactions and edges representing the conflicts. If S is serializable, which one of the following orderings of the vertices of the precedence graph is guaranteed to yield a serial schedule? [GATE – 2016]

a. Topological order
b. Depth-first order
c. Breadth-first order
d. Ascending order of transaction indices

Answer : a)


7. Consider the following database schedule with two transactions, T1 and T2.

S = r2(X); r1(X); r2(Y); w1(X); r1(Y); w2(X); a1; a2

where ri(Z) denotes a read operation by transaction Ti on a variable Z, wi(Z) denotes a write operation by Ti on a variable Z and ai denotes an abort by transaction Ti.

Which one of the following statements about the above schedule is TRUE? [GATE – 2016]

a. S is non-recoverable
b. S is recoverable, but has a cascading abort
c. S does not have a cascading abort
d. S is strict

Answer : c)
DBMS |Gate-2016|


8. Consider the following database table named water_schemes :

The number of tuples returned by the following SQL query is _________. [GATE – 2016]

with total(name, capacity) as
select district_name, sum(capacity)
from water_schemes
group by district_name
with total_avg(capacity) as
select avg(capacity)
from total
select name
from total, total_avg
where total.capacity ≥ total_avg.capacity

a. 2
b. 3
c. 4
d. 5

Answer : a)


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