Showing posts with label Distributed Database Quiz. Show all posts
Showing posts with label Distributed Database Quiz. Show all posts

Tuesday, April 21, 2020

Multiple choice interview questions on distributed database

Multiple choice interview questions on distributed database


Multiple Choice Questions with Answers in Distributed Database



1. Which of the following would improve the availability of resources especially for reading in a distributed database system?
a) Fragmentation of database
b) Replication of database
c) Defragmentation of database
d) Tuning of database

View Answer

Answer: (b) Replication of database
Replication in distributed database system is a concept of having multiple copies of same data at different sites to increase the availability of resources.

2. ______________ is very much required to process a query in a distributed database.
a) Global System Catalog
b) Database Views
c) Triggers
d) None of the above

View Answer

Answer: (a) Global System Catalog
Data dictionary is an important component in DBMS. It is used for manipulating information regarding all database components in a DBMS. It stores information regarding tables, views, name of the tables, attributes, constraint details etc. Global System Catalog is just like Data Dictionary for Distributed Database System. It stores information like what and where about the data in a DDB.

3. Reliability and availability of a “Centralized Data Allocation” method is ___________ when compared to a “Completely Replicated Data Allocation“.
a) Highest
b) Average
c) Lowest
d) Not applicable

View Answer

Answer: (c) Lowest
Replication in distributed database system is a concept of having multiple copies of same data at different sites to increase the availability of resources.
In a centralized data allocation method only one copy of data available. Hence, availability is lowest. Due to only one copy of data, it is prone to single point of failure.
In a completely replicated data allocation method, due to availability of more than one copy of same data, the reliability and availability is high compare to centralized data allocation method.

4. If one site ABORTs while processing part of a distributed transaction t, all other sites processing part of t will also ABORT t. Which of the following ensures this?
a) Two phase locking protocol
b) Two phase commit protocol
c) Three phase commit protocol
d) All of the above

View Answer

Answer: (b) Two phase commit protocol
In two phase commit protocol, the transaction coordinator decides to ABORT the entire transaction if any of the participating sites cannot commit for some reasons.

5. Which of the following transparencies in distributed database design requires the end user or programmer to specify the database fragment names but need not specify where these fragments are located?
a) Transaction
b) Location
c) Local mapping
d) Fragmentation

View Answer

Answer: (b) Location
Location transparency refers to the fact that the command used to perform a task is independent of both the location of the data and the system on which an operation is carried out.



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Distributed database multiple choice questions with answers

important quiz questions in DDB

one mark questions in distributed database for university examinations



Wednesday, April 15, 2020

Multiple Choice Questions MCQ on Distributed Database

Multiple Choice Questions MCQ on Distributed Database with answers



Distributed Database – Multiple Choice Questions with Answers

1. Let us suppose that in a distributed database, during a transaction T1, one of the sites, say S1, is failed. When recovers, the site S1 has to check its log file (log based recovery) to decide the next move on the transaction T1. If the log contains a <commit T> record, what the site S1 has to do?
a) Need not do anything
b) Perform Undo
c) Perform Redo
d) Abort the transaction

2. Global Wait-for graph is used for ________________  in Distributed database.
a) Handling concurrency control
b) Handling failures
c) Handling deadlock
d)  None of the above

3. In Distributed database, ______________ are the transactions for which a <ready T> log is found in the log file, but neither a <commit T> log nor an <abort T> log is found.
a) In-doubt transactions
b) Serialized transactions
c) Cascadeless transactions
d) Distributed transactions

4. While using commit protocols for handling atomicity issues, the distributed database system may enter into a situation called Blocking problem. Which of the following commit protocols can avoid Blocking problem?
a) Two-phase commit protocol
b) Three-phase commit protocol
c) Both of the above
d) None of the above

5. Which of the following concurrency control protocol is suitable for an application where frequency of read operation is much greater than that of write operation?
a) Majority protocol
b) Quorum-consensus protocol
c) Biased protocol
d) Single lock protocol

6. Which of the following parallel database architectures is/are mainly used by distributed database system?
a) Shared Memory
b) Shared Disk
c) Shared Nothing
d) Hierarchical

7. Which of the following is not a promise of distributed database?
a) Network Transparency
b) Replication Transparency
c) Fragmentation Transparency
d) None of the above

8. All sites in a distributed database commit at exactly the same instant. TRUE/FALSE
a) TRUE
b) FALSE

9. The real use of the Two-phase commit protocol is  ______________
a) Deadlock will not occur
b) Concurrency control can be avoided
c) Atomicity, i.e, all-or-nothing commits at all sites
d) None of the above

10. Read one, write all available protocol is used to increase ___________ in a distributed database system.
a) Availability
b) Robustness
c) Both Availability and Robustness
d) Neither Availability nor Robustness



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Distributed database multiple choice questions with answers

important quiz questions in DDB

one mark questions in distributed database for university examinations

Tuesday, April 14, 2020

MCQ on distributed and parallel database concepts

MCQ on distributed and parallel database concepts, Interview questions with answers in distributed database



Distribute and Parallel Database – Quiz


1. When a participating site S1 decides to commit the transaction T upon receiving the <prepare T> message from the coordinator, it sends _____ message to the coordinator site.
a) <prepare T>
b) <commit T>
c) <ready T>
d) <abort T>
Answer: (c)
According to two phase commit protocol, if a site is ready for committing a transaction which was already initiated by a coordinator with a <prepare T> message, it will write a <ready T> message into its log, store in its stable storage and send the same to the coordinator site.

2. Why in two phase commit protocol does a participating site first write the decision in its log file before communicating it with the coordinator site?

a) to decide the fate of the transaction if a failure happens
b) to send the all the decisions at once to the coordinator site to reduce the cost.
c) both (a) and (b)
d) neither (a) nor (b)
Answer: (a)
The participant must be able to tell the difference between a crash/failure that occurred before it voted ‘ready’ to Commit from a failure that occurred after it voted ‘ready’ to commit. If on recovery, the participant finds ‘Prepared’ in its log, it knows it voted in favour of committing the transaction, but it does not know the final decision. So it must inquire the Coordinator. If the decision from the Coordinator is to abort, then the participant aborts and rolls-back its sub-transaction.

3. In two-phase commit (2PC) protocol, who can cause a transaction to abort?

a) Coordinator
b) Participating site
c) Both coordinator and participating site
d) Third party site
Answer: (c)

In 2PC, both the coordinator site and the participating site can cause a transaction to abort.

How participating site can do? - If a participating site is not ready to commit a transaction T, then it writes <abort T> in its log file and communicate the same to the coordinator site.
How a coordinator site can do? – If any of the participating sites is not ready to commit, then coordinator decides not to commit and intimate the same to other participating sites.

4. To increase the throughput and response time of the system especially when there are lots of smaller queries, which type of parallelism is most likely to perform better?

a) Intra-query parallelism
b) Inter-query parallelism
c) Inter-operation parallelism
d) Intra-operation parallelism
Answer: (b)
Small queries do not consume much time of the CPU. Inter-query parallelism is a form of parallelism where many different Queries or Transactions are executed in parallel with one another on many processors. It also increases the number of transactions executed in a given time.

5. Which of the following helps in implementing inter-operation parallelism?

a) Interdependent parallelism
b) Intra-query parallelism
c) Inter-query parallelism
d) Pipelined parallelism
Answer: (d)

Inter-operation parallelism is the concept of executing multiple operations of same query in parallel.

The idea behind the pipelined parallelism is to consume the result produced by one operation by the next operation in the pipeline.

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