Database Management Systems Set 2

Database Management Systems

Questions 11 to 20



11.
A transaction completes its execution is said to be
(a)
Committed
(b)
Aborted
(c)
Rolled back
(d)
Failed
(e)
Partially committed.
12.
The process of managing simultaneous operations on the database without having them interfere with one another is
(a)
Serializability
(b)
Recoverability
(c)
Concurrency control
(d)
Transaction management
(e)
None of the above.
13.
A schedule where the operations of each transaction are executed consecutively without any other interference from other transactions is called 
(a)
Non-serial schedule
(b)
Serial schedule
(c)
Recoverable schedule
(d)
Non-recoverable schedule
(e)
Concurrent schedule.
14.
Which of the following is not a deadlock handling strategy?
(a)
Deadlock prevention
(b)
Timeout
(c)
Deadlock detection and recovery 
(d)
Deadlock annihilation
(e)
None of the above.
15.
Which of the following does refer to the size of the data item chosen as the unit of protection by a concurrency control program?
(a)
Granularity
(b)
Lock
(c)
Starvation
(d)
Timestamp
(e)
Time based.
16.
Which of the following hashing techniques does allow a hash file to expand and shrink its number of buckets dynamically without needing a directory?
(a)
Linear hashing
(b)
Extensible hashing
(c)
Internal hashing
(d)
External hashing
(e)
Non-linear hashing.
17.
Which of the following indexes is based on the values being uniformly distributed using a mathematical function?
(a)
Ordered index
(b)
Hashed index
(c)
Dense index
(d)
Sparse index
(e)
Secondary index.
18.
A join in which the joining condition is based on equality between values in the common columns is called
(a)
Equi-join
(b)
Uni-lateral join
(c)
Natural join
(d)
Both (a) and (c) above
(e)
Both (b) and (c) above.
19.
A type of query that is placed within a WHERE or HAVING clause of another query is called
(a)
Master query
(b)
Query
(c)
Superquery
(d)
Multi-query
(e)
Subquery.
20.
The entity integrity rule states that
(a)
No primary key attribute can be null 
(b)
Referential integrity must be maintained across all entities
(c)
Each entity must have a primary key
(d)
A primary key must have only one attribute
(e)
Foreign key attribute can be Null.

Answers


11.
Answer : (a)
Reason:  A transaction the completes its execution is said to be Committed.
12.
Answer : (c)
Reason:  The process of managing simultaneous operations on the database without having them interfere with one another is Concurrency control.
13.
Answer : (b)
Reason:  A schedule where the operations of each transaction are executed consecutively without any other interference from other transactions is called  Serial schedule.
14.
Answer : (d)
Reason:  Deadlock annihilation  is NOT a deadlock handling strategy.
15.
Answer : (a)
Reason:  Granularity refer to the size of the data item chosen as the unit of protection by a concurrency control program.
16.
Answer : (b)
Reason:  Extensible hashing techniques does allow a hash file to expand and shrink its number of buckets dynamically without needing a directory.
17.
Answer : (b)
Reason:  Extensible hashing techniques does allow a hash file to expand and shrink its number of buckets dynamically without needing a directory.
18.
Answer : (d)
Reason:  The equi-join is a join in which records are retrieved based on whether the join fields have matching values in both tables. That may seem like just a definition of a join, but it isn't. An example of a non-equal join is a join where records in the first table are joined to those records in the second table where the joined field in the first table is greater than (instead of equal to) the joined field in the second table (or less than, or anything besides equal to). Naturally, this returns more records than an equi-join.
              A natural join is one in which only one of the two tables’ joined fields is returned. Since these two fields are by definition identical in an equi-join, it is redundant to include both. For a non-equal join, it is important to include both of those fields. So, equi-joins and natural joins go together.
19.
Answer : (e)
Reason:  A type of query that is placed within a WHERE or HAVING clause of another query is called Sub query
20.
Answer : (a)
Reason:  The entity integrity rule states that no primary key attribute can be null

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