Distributed database and parallel database quiz questions with answers SET 09

Distributed database quiz questions with answers, MCQ in distributed database, solved exam questions in distributed and parallel database, distributed query processing, data replication

MCQ in Distributed and Parallel Database with Solutions

1. Which of the following parallelism enables the execution of multiple queries generated by concurrent transactions?

(a) Inter-query parallelism

(b) Intra-query parallelism

(c) Independent parallelism

(d) None of the above.

Click here to view answer and explanation

Ans : (a)

Answer: (a) Inter-query parallelism Inter-query parallelism is about executing multiple queries simultaneously. The queries are executed in this way helps in improving the transaction throughput, ie., to increase the number of transactions executed simultaneously at a time.

 

2. Why data fragmentation and distribution is considered as a desirable property?

(a) Reduced data transmission cost

(b) Reduces table size

(c) Availability

(d) All of the above.

Click here to view answer and explanation

Ans : (d)

Answer: (d) All of the above Fragmentation is desirable because it enables the placement of data in close proximity to its place of use, thus potentially reducing transmission cost, and it reduces the size of relations that are involved in user queries. Due to the placement of data in various locations, as per the used technology, some or all of the data are available always.

 

3. Suppose the users of a distributed database system are permitted to execute read-only queries. Which of the following would be the best solution for such an access?

(a) Horizontal fragmentation

(b) Vertical fragmentation

(c) Replication

(d) None of the above.

Click here to view answer and explanation

Ans : (c)

Answer: (c) Replication If only read-only access is given to all users, then the best solution will be to replicate the database and store the replicated data at each site. This will increase the availability and no additional hidden costs are involved. Only the update (which may be performed by the administrators, as per the question) has to be propagated to each site. Even the update may not be much frequent for this scenario.

 

4. In some cases of query processing, the operations in a single query are executed at the same time or in random order. What type of parallelism is this? Choose the most relevant one from the following;

(a) Intra-operation parallelism

(b) Pipelined parallelism

(c) Independent parallelism

(d) Inter-operation parallelism

Click here to view answer and explanation

Ans : (c)

Answer: (c) Independent parallelism Independent parallelism is a type of inter-operation parallelism. As per this form of parallelism, operations in a query that do not depend on one another can be executed in parallel. For example, a natural join operation involving more than 3 operands can be executed in parallel. This type of parallelism is possible only when the operations do not involve the same data.

 

5. In distributed database environment, the execution of set of distributed transactions is said to be serializable if an only if

(a) the execution of the set of transactions at each site is serializable

(b) the serialization orders of set of transactions at all the sites are identical

(c) the set of transactions that are not in serial order

(d) the serialization orders of set of transactions at all the sites are not identical

Click here to view answer and explanation

Ans : (a) and (b)

Answer: (a) the execution of the set of transactions at each site is serializable and (b) the serialization orders of set of transactions at all the sites are identical The execution of a set of distributed transactions is serializable if and only if the execution of the set of transactions at each site is serializable, and the serialization orders of these transactions at all these sites are identical. This kind of global serializability is enforced by distributed concurrency control algorithms.

 

******************

Related links:

• Go to Distributed Database Quiz page

• Go to Database Management Systems Quiz page

• Go to Distributed Database Home page

 

Distributed database multiple choice questions with answers

important quiz questions in DDB

one mark questions in distributed database for university examinations