Distributed Databases - Study Mode
[#1] Databases that are stored on computers at multiple locations and are not interconnected by a network are known as distributed databases.
Correct Answer
(B) False
Explanation
Solution: The statement is incorrect. Databases that are stored on computers at multiple locations and are not interconnected by a network are not considered distributed databases. Distributed databases, by definition, involve data stored on multiple interconnected computers or nodes, allowing for distributed data processing and access. Option A: True This option contradicts the statement provided in the question. Distributed databases require interconnected computers or nodes to enable communication and data sharing among different locations. Therefore, the statement "Databases that are stored on computers at multiple locations and are not interconnected by a network are known as distributed databases" is false. Option B: False This option correctly identifies the statement as false. The absence of network connectivity between computers at multiple locations disqualifies the scenario from being classified as a distributed database. Distributed databases rely on network communication to coordinate data access, sharing, and processing across distributed locations. Therefore, in response to the question, the correct option is False (Option B).
[#2] An increasingly popular option for data distribution as well as for fault tolerance of any database is to store a separate copy of the database at each of two or more sites.
Correct Answer
(A) True
Explanation
Solution: The statement is true. Storing a separate copy of the database at each of two or more sites is indeed an increasingly popular option for data distribution and fault tolerance in databases, particularly in distributed database environments. Option A: True This option correctly affirms the statement provided in the question. Storing separate copies of the database at multiple sites enhances data distribution, availability, and fault tolerance. Each site maintains its own copy of the database, allowing for local access to data and reducing dependencies on a single central database server. In the event of a site failure or network partition, other sites can continue to operate independently, ensuring continuous access to data and minimal disruption to database operations. Option B: False This option contradicts the statement provided in the question. Storing separate copies of the database at multiple sites is indeed a popular strategy for improving data distribution and fault tolerance in distributed database systems. It offers benefits such as improved data availability, reduced network dependencies, and enhanced resilience against site failures. Therefore, in response to the question, the correct option is True (Option A).
[#3] Asynchronous technology can result in unsatisfactorily slow response time because the distributed DBMS is spending considerable time checking that an update is accurately and completely propagated across the network.
Correct Answer
(A) True
Explanation
Solution: The statement is true. Asynchronous replication technology can lead to unsatisfactorily slow response times because the distributed DBMS spends considerable time ensuring that updates are accurately and completely propagated across the network. Option A: True This option correctly affirms the statement provided in the question. In asynchronous replication, updates are propagated across the network with a delay, and the distributed DBMS must verify that updates are accurately and completely propagated to all replicas before committing the transaction. This verification process can introduce latency and overhead, resulting in slower response times, especially for transactions that require immediate confirmation or synchronization across distributed nodes. Option B: False This option contradicts the statement provided in the question. Asynchronous replication technology, by its nature, introduces delays in propagating updates across the network to achieve eventual consistency. These delays can indeed lead to slower response times, particularly in scenarios where immediate data consistency or synchronization is required. Therefore, in response to the question, the correct option is True (Option A).
[#4] A distributed unit of work allows various statements within a unit of work to refer to multiple remote DBMS locations.
Correct Answer
(A) True
Explanation
Solution: The statement is true. In a distributed unit of work, various statements within a unit of work can indeed refer to multiple remote DBMS locations, allowing for coordinated transactions across distributed databases. Option A: True This option correctly affirms the statement provided in the question. A distributed unit of work enables transactions to span multiple remote DBMS locations, allowing for coordinated data access and updates across distributed databases. This capability is essential for maintaining data consistency and integrity in distributed database environments, where transactions may involve accessing or modifying data stored on different nodes or sites. Option B: False This option contradicts the statement provided in the question. A distributed unit of work is specifically designed to support transactions that involve multiple remote DBMS locations. By allowing various statements within a unit of work to refer to multiple remote locations, distributed units of work facilitate the execution of distributed transactions and ensure that changes to the database are coordinated and consistent across all participating nodes. Therefore, in response to the question, the correct option is True (Option A).
[#5] Data replication is favored where most process requests are read-only and where the data are relatively static.
Correct Answer
(A) True
Explanation
Solution: The statement is true. Data replication is indeed favored in scenarios where most process requests are read-only and where the data are relatively static, as it offers benefits such as improved read performance, enhanced fault tolerance, and increased availability. Option A: True This option correctly affirms the statement provided in the question. Data replication is advantageous in environments where the majority of process requests involve reading data rather than writing or updating it. By replicating data across multiple nodes or sites, read requests can be serviced locally, leading to faster response times and reduced network latency. Additionally, data replication enhances fault tolerance by ensuring that copies of data are available on multiple nodes, reducing the risk of data loss or unavailability due to node failures. Furthermore, in scenarios where the data are relatively static and do not change frequently, data replication provides a cost-effective solution for distributing data and improving access performance without the need for complex synchronization mechanisms. Option B: False This option contradicts the statement provided in the question. Data replication is indeed favored in scenarios where read-only process requests are predominant and where the data are relatively static. In such cases, data replication offers advantages in terms of read performance, fault tolerance, and availability, making it a suitable strategy for improving data access and reliability in distributed database environments. Therefore, in response to the question, the correct option is True (Option A).