Distributed Database Systems Curriculum Quiz
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Questions and Answers

What is the main benefit of locating data closer to their access points in a distributed database system?

  • Simplified query processing
  • Reduction in response time (correct)
  • Improved system reliability
  • Enhanced data security

    • What does the term 'logical data item' refer to in the execution model of replicated databases?

  • The synchronization process of the data copies
  • The process of data replication
  • The actual physical copy of the data
  • The original data item being replicated (correct)

    • Which factor dictates the maintenance of multiple data copies as part of their operational specifications in distributed databases?

  • System availability
  • Data replication challenges
  • Scalability concerns
  • Application requirements (correct)

    • What is one of the challenges posed by data replication in distributed databases?

    <p>Synchronization of different copies</p> Signup and view all the answers

    In the context of distributed databases, what is the purpose of data replication for scalability?

    <p>To support growth with acceptable response times</p> Signup and view all the answers

    What is the responsibility of the replica control protocol?

    <p>Mapping logical data item operations to physical data items</p> Signup and view all the answers

    In a partially replicated database, what type of transactions are considered local transactions?

    <p>Transactions that access only non-replicated data items</p> Signup and view all the answers

    What does a mutually consistent state in a replicated database ensure?

    <p>All replicas of each data item have identical values</p> Signup and view all the answers

    What is the characteristic of centralized update techniques?

    <p>They perform updates first on a master copy</p> Signup and view all the answers

    What is the primary responsibility of the replica control protocol in a replicated database system?

    <p>Mapping user transactions' read and write operations to physical data items</p> Signup and view all the answers

    What type of transactions have to be executed at multiple sites in a partially replicated database?

    <p>Global transactions that access replicated data items</p> Signup and view all the answers

    When are updates performed on a replica considered centralized?

    <p>When they perform updates first on a master copy</p> Signup and view all the answers

    What characterizes a distributed update technique?

    <p>Allowing updates over any replica</p> Signup and view all the answers

    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:

    <p>One-copy equivalence (single system image)</p> Signup and view all the answers

    What does reliability refer to in the context of distributed database systems?

    <p>The probability that the system has not experienced any failures within a given time period.</p> Signup and view all the answers

    What is the main problem related to reliability in maintaining atomicity and durability properties of transactions in distributed database systems?

    <p>Distributed Concurrency Control</p> Signup and view all the answers

    What type of transactions are considered local transactions in a partially replicated database?

    <p>Read-only transactions</p> Signup and view all the answers

    What is the primary purpose of data replication in distributed databases?

    <p>To achieve high availability</p> Signup and view all the answers

    What does availability refer to in the context of distributed database systems?

    <p>The probability that the system is operational according to its specification at a given point in time.</p> Signup and view all the answers

    Which factor dictates the maintenance of multiple data copies as part of their operational specifications in distributed databases?

    <p>Distributed DBMS Reliability</p> Signup and view all the answers

    What is the expected time between subsequent failures in a system with repair?

    <p>Mean time between failures (MTBF)</p> Signup and view all the answers

    What is the expected time to repair a failed system known as?

    <p>Mean time to repair (MTTR)</p> Signup and view all the answers

    What kind of failures can lead to total failure or partial failure in a distributed DBMS?

    <p>Site (system) failures</p> Signup and view all the answers

    What does the local recovery manager (LRM) relate to in the execution of commands?

    <p>Buffer manager</p> Signup and view all the answers

    When does the buffer manager read a page of data into an empty database buffer?

    <p>When executing a fetch command</p> Signup and view all the answers

    What type of update causes a change in one or more data values on pages in the database buffers?

    <p>In-place update</p> Signup and view all the answers

    What strategy dictates when to write log records into stable store?

    <p>Write–Ahead Log Protocol</p> Signup and view all the answers

    Can the buffer manager decide to write some of the buffer pages being accessed by a transaction into stable storage?

    <p>Yes, depending on LRM's instruction</p> Signup and view all the answers

    What decision does the LRM force the buffer manager to make at the end of a transaction's execution?

    <p>Flush/no-flush decision</p> Signup and view all the answers

    What kind of redo/undo does No-Fix/No-Flush strategy involve?

    <p>No-Fix/No-Flush redo / undo</p> Signup and view all the answers

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