Distributed Databases - Database MCQ Questions and answers- Technical Aptitude Page-2 section-1

11.
A distributed database is which of the following?

A. A single logical database that is spread to multiple locations and is interconnected by a network

B. A loose collection of file that is spread to multiple locations and is interconnected by a network

C. A single logical database that is limited to one location.

D. A loose collection of file that is limited to one location.

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Answer & Solution

Answer: Option A

Solution:

A distributed database is a single logical database that is spread across multiple locations and interconnected by a network, enabling distributed data processing and access.

Option A: A single logical database that is spread to multiple locations and is interconnected by a network
This option correctly describes a distributed database. It emphasizes that although the database is distributed across multiple locations, it functions as a single logical unit, allowing users to access and manipulate data as if it were stored in a centralized location. The distributed nature of the database enables data sharing, replication, and distributed query processing over a network.

Option B: A loose collection of file that is spread to multiple locations and is interconnected by a network
This option describes a distributed file system rather than a distributed database. In a distributed file system, files are distributed across multiple locations and interconnected by a network, but there is no centralized control or management of data as in a distributed database.

Option C: A single logical database that is limited to one location
This option describes a centralized database rather than a distributed database. In a centralized database, all data is stored and managed within a single location or server, without distributed storage or processing capabilities.

Option D: A loose collection of file that is limited to one location
This option describes a local file system rather than a distributed database. In a local file system, files are stored and managed within a single location or device, with no distribution of data across multiple locations.

Therefore, in response to the question, the correct option is Option A: A single logical database that is spread to multiple locations and is interconnected by a network.

12.
A semijoin is which of the following?

A. Only the joining attributes are sent from one site to another and then all of the rows are returned.

B. All of the attributes are sent from one site to another and then only the required rows are returned.

C. Only the joining attributes are sent from one site to another and then only the required rows are returned.

D. None of the above

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13.
Which of the following is a disadvantage of replication?

A. Reduced network traffic

B. If the database fails at one site, a copy can be located at another site.

C. Each site must have the same storage capacity.

D. Each transaction may proceed without coordination across the network.

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Answer & Solution

Answer: Option C

Solution:

While replication offers several advantages in a distributed database system, it also comes with certain disadvantages or limitations.

Option A: Reduced network traffic
This option describes a potential advantage of replication rather than a disadvantage. Replication can indeed reduce network traffic by allowing local access to data copies, thereby minimizing the need for data transfer across network links.

Option B: If the database fails at one site, a copy can be located at another site.
This option highlights a benefit of replication in terms of fault tolerance and high availability. Having copies of the database at multiple sites ensures data redundancy and resilience against failures. It does not represent a disadvantage of replication.

Option C: Each site must have the same storage capacity.
This option correctly identifies a disadvantage of replication. In a replication setup, each site hosting a copy of the database must have sufficient storage capacity to accommodate the replicated data. Ensuring uniform storage capacity across all sites can be challenging and may lead to resource constraints or inefficiencies, especially in heterogeneous environments where sites have different storage capabilities or requirements.

Option D: Each transaction may proceed without coordination across the network.
This option describes a characteristic of loosely coupled distributed systems rather than a specific disadvantage of replication. In distributed databases with replication, transactions may indeed proceed independently at each site without requiring immediate coordination across the network. While this decentralization of transaction processing can improve performance and scalability, it also introduces complexities related to maintaining data consistency and isolation.

Therefore, in the context of disadvantages of replication in a distributed database system, the correct option is Each site must have the same storage capacity (Option C).

14.
A distributed database can use which of the following strategies?

A. Totally centralized at one location and accessed by many sites

B. Partially or totally replicated across sites

C. Partitioned into segments at different sites

D. All of the above

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Answer & Solution

Answer: Option D

Solution:

A distributed database can employ various strategies to manage its data across multiple sites.

Option A: Totally centralized at one location and accessed by many sites
In this strategy, although the database is centralized at one location, it is accessed by multiple sites. This approach may involve having a central server that holds the entire database, and other sites access this central database over a network. While it simplifies data management and ensures data consistency, it can lead to network congestion and single points of failure.

Option B: Partially or totally replicated across sites
Replication involves creating and maintaining copies of data across multiple sites. In a distributed database, data can be partially or entirely replicated across sites to improve data availability, fault tolerance, and performance. Replication allows local access to data, reducing the need for network communication and enhancing responsiveness. However, it requires mechanisms to ensure data consistency among replicas.

Option C: Partitioned into segments at different sites
Partitioning, also known as sharding, involves dividing the database into segments or partitions, with each partition stored at a different site. This strategy aims to distribute data and workload evenly across sites, improving scalability and performance. By partitioning data, queries can be executed locally on the site where the relevant data resides, reducing network overhead and enhancing efficiency.

Option D: All of the above
All the mentioned strategies—centralization, replication, and partitioning—are viable approaches for managing data in a distributed database. Depending on the requirements of the application, a distributed database system may utilize one or a combination of these strategies to achieve its goals, such as improving performance, availability, and fault tolerance.

Therefore, in the context of a distributed database, the correct option is All of the above (Option D).

15.
Which of the following is not one of the stages in the evolution of distributed DBMS?

A. Unit of work

B. Remote unit of work

C. Distributed unit of Work

D. Distributed request

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Answer & Solution

Answer: Option D

Solution:

The evolution of distributed Database Management Systems (DBMS) involves several stages, each representing advancements in architecture and functionality to support distributed data processing.

Option A: Unit of work
The concept of a unit of work represents the earliest stage in the evolution of distributed DBMS. In this stage, transactions are processed as atomic units of work within a single centralized database system. Transactions are executed sequentially, and concurrency control is limited to within the boundaries of a single database.

Option B: Remote unit of work
The stage of remote unit of work builds upon the concept of a unit of work by introducing the capability to execute transactions that involve accessing data located on remote sites. In this stage, transactions may span multiple nodes or sites in a distributed environment, but the processing is still coordinated by a central authority.

Option C: Distributed unit of work
The distributed unit of work stage represents a further advancement where transactions can be processed independently at each participating node or site in a distributed system. Transactions are decomposed into subtransactions, and each subtransaction can be executed autonomously at its respective node. Coordination and synchronization mechanisms are implemented to ensure consistency and isolation across distributed transactions.

Option D: Distributed request
This option does not correspond to a recognized stage in the evolution of distributed DBMS. While distributed requests are integral to distributed database systems, they are typically associated with the execution of transactions or operations rather than representing a distinct evolutionary stage.

Therefore, in the context of the stages in the evolution of distributed DBMS, the correct option is Distributed request (Option D).

16.
With failure transparency, all of the actions of a transaction are committed or none of them are committed.

A. True

B. False

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17.
Each site (or node) in a distributed system is subject to the same types of failure as in a centralized system.

A. True

B. False

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18.
Replication may use either synchronous or asynchronous distributed database technologies, although asynchronous technologies are more typical in a replicated environment.

A. True

B. False

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19.
Synchronization for pull replication is less disruptive and occurs only when needed by each site, not when a central master site thinks it is best to update.

A. True

B. False

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20.
With asynchronous technology, if any copy of a data item is updated anywhere on the network, the same update is immediately applied to all other copies or it is aborted.

A. True

B. False

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Distributed Databases - Database MCQ Questions and answers- Technical Aptitude

11. A distributed database is which of the following?

Answer & Solution

12. A semijoin is which of the following?

Answer & Solution

13. Which of the following is a disadvantage of replication?

Answer & Solution

14. A distributed database can use which of the following strategies?

Answer & Solution

15. Which of the following is not one of the stages in the evolution of distributed DBMS?

Answer & Solution

16. With failure transparency, all of the actions of a transaction are committed or none of them are committed.

Answer & Solution

17. Each site (or node) in a distributed system is subject to the same types of failure as in a centralized system.

Answer & Solution

18. Replication may use either synchronous or asynchronous distributed database technologies, although asynchronous technologies are more typical in a replicated environment.

Answer & Solution

19. Synchronization for pull replication is less disruptive and occurs only when needed by each site, not when a central master site thinks it is best to update.

Answer & Solution

20. With asynchronous technology, if any copy of a data item is updated anywhere on the network, the same update is immediately applied to all other copies or it is aborted.

Answer & Solution

11.
A distributed database is which of the following?

12.
A semijoin is which of the following?

13.
Which of the following is a disadvantage of replication?

14.
A distributed database can use which of the following strategies?

15.
Which of the following is not one of the stages in the evolution of distributed DBMS?

16.
With failure transparency, all of the actions of a transaction are committed or none of them are committed.

17.
Each site (or node) in a distributed system is subject to the same types of failure as in a centralized system.

18.
Replication may use either synchronous or asynchronous distributed database technologies, although asynchronous technologies are more typical in a replicated environment.

19.
Synchronization for pull replication is less disruptive and occurs only when needed by each site, not when a central master site thinks it is best to update.

20.
With asynchronous technology, if any copy of a data item is updated anywhere on the network, the same update is immediately applied to all other copies or it is aborted.