30 Questions
What is the main benefit of locating data closer to their access points in a distributed database system?
Reduction in response time
What does the term 'logical data item' refer to in the execution model of replicated databases?
The original data item being replicated
Which factor dictates the maintenance of multiple data copies as part of their operational specifications in distributed databases?
Application requirements
What is one of the challenges posed by data replication in distributed databases?
Synchronization of different copies
In the context of distributed databases, what is the purpose of data replication for scalability?
To support growth with acceptable response times
What is the responsibility of the replica control protocol?
Mapping logical data item operations to physical data items
In a partially replicated database, what type of transactions are considered local transactions?
Transactions that access only non-replicated data items
What does a mutually consistent state in a replicated database ensure?
All replicas of each data item have identical values
What is the characteristic of centralized update techniques?
They perform updates first on a master copy
What is the primary responsibility of the replica control protocol in a replicated database system?
Mapping user transactions' read and write operations to physical data items
What type of transactions have to be executed at multiple sites in a partially replicated database?
Global transactions that access replicated data items
When are updates performed on a replica considered centralized?
When they perform updates first on a master copy
What characterizes a distributed update technique?
Allowing updates over any replica
The effect of transactions performed by clients on replicated objects should be the same as if they had been performed on a single set of objects. This statement refers to:
One-copy equivalence (single system image)
What does reliability refer to in the context of distributed database systems?
The probability that the system has not experienced any failures within a given time period.
What is the main problem related to reliability in maintaining atomicity and durability properties of transactions in distributed database systems?
Distributed Concurrency Control
What type of transactions are considered local transactions in a partially replicated database?
Read-only transactions
What is the primary purpose of data replication in distributed databases?
To achieve high availability
What does availability refer to in the context of distributed database systems?
The probability that the system is operational according to its specification at a given point in time.
Which factor dictates the maintenance of multiple data copies as part of their operational specifications in distributed databases?
Distributed DBMS Reliability
What is the expected time between subsequent failures in a system with repair?
Mean time between failures (MTBF)
What is the expected time to repair a failed system known as?
Mean time to repair (MTTR)
What kind of failures can lead to total failure or partial failure in a distributed DBMS?
Site (system) failures
What does the local recovery manager (LRM) relate to in the execution of commands?
Buffer manager
When does the buffer manager read a page of data into an empty database buffer?
When executing a fetch command
What type of update causes a change in one or more data values on pages in the database buffers?
In-place update
What strategy dictates when to write log records into stable store?
Write–Ahead Log Protocol
Can the buffer manager decide to write some of the buffer pages being accessed by a transaction into stable storage?
Yes, depending on LRM's instruction
What decision does the LRM force the buffer manager to make at the end of a transaction's execution?
Flush/no-flush decision
What kind of redo/undo does No-Fix/No-Flush strategy involve?
No-Fix/No-Flush redo / undo
Test your knowledge of distributed databases with this quiz based on the curriculum topics including distributed database design, query processing, distributed transaction processing, data replication, and more.
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