IS411P Distributed Database Systems Quiz 2

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Questions and Answers

What is the main purpose of concurrency control algorithms in distributed database systems?

  • To enforce atomicity and durability measures
  • To ensure that concurrent transactions see a consistent database state (correct)
  • To handle integrity enforcement for individual transactions
  • To optimize query processing and data replication

Which property do reliability measures enforce in distributed database systems?

  • Durability (correct)
  • Atomicity
  • Isolation
  • Consistency

What aspect of distributed database systems does data replication primarily address?

  • Distributed transaction processing
  • Concurrency control
  • Reliability and fault tolerance (correct)
  • Query processing and optimization

What is the main role of distributed DBMS reliability measures?

<p>Ensure atomicity and durability of distributed transactions (A)</p> Signup and view all the answers

In distributed database systems, what is the main function of distributed transaction processing?

<p>Maintain consistency between concurrent transactions (C)</p> Signup and view all the answers

What is the primary role of data replication in distributed database systems?

<p>Providing fault tolerance and reliability (B)</p> Signup and view all the answers

In timestamp-based concurrency control algorithms, how are serialization orders established?

<p>By assigning each transaction a unique timestamp at initiation (C)</p> Signup and view all the answers

What is the preferred method for assigning timestamps to transactions in a distributed DBMS?

<p>Allowing each site to autonomously assign timestamps based on its local counter (B)</p> Signup and view all the answers

What does a timestamp consist of in the context of a distributed DBMS?

<p>A local counter value and a site identifier (D)</p> Signup and view all the answers

What is the role of the coordinating TM in the basic TO algorithm?

<p>Assigning timestamps to transactions and determining the sites where data items are stored (D)</p> Signup and view all the answers

What is the TO Rule in the context of the basic TO algorithm?

<p>It enforces a specific order of execution for conflicting operations (C)</p> Signup and view all the answers

What happens if a new operation belongs to a transaction that is younger than all conflicting operations already scheduled in the basic TO algorithm?

<p>The operation is accepted and executed immediately (D)</p> Signup and view all the answers

What is the purpose of assigning read and write timestamps to data items in the basic TO algorithm?

<p>To identify the oldest transaction that has read or written (updated) each data item (C)</p> Signup and view all the answers

What is a potential drawback of the basic TO algorithm?

<p>It causes excessive restarts of transactions due to no delaying (C)</p> Signup and view all the answers

What is one of the key differences between basic TO and conservative TO algorithms?

<p>Basic TO algorithm never causes operations to wait, whereas conservative TO algorithms introduce waiting times. (D)</p> Signup and view all the answers

How do conservative TO algorithms attempt to lower system overhead?

<p>By delaying each operation until there is no conflict with previously scheduled operations (C)</p> Signup and view all the answers

Why does the conservative TO algorithm attempt to reduce transaction restarts?

<p>To lower system overhead and reduce operational disruptions caused by restarts (C)</p> Signup and view all the answers

What drawback does the conservative TO algorithm aim to mitigate compared to the basic TO algorithm?

<p>The excessive restarts of transactions due to no delaying (D)</p> Signup and view all the answers

What does the conservative TO algorithm prioritize over immediate acceptance of new operations?

<p>Reduction of system resource utilization through delayed execution (A)</p> Signup and view all the answers

What is a transaction in the context of a distributed database?

<p>A transaction is a collection of actions that make consistent transformations of system states while preserving system consistency.</p> Signup and view all the answers

What do concurrency control algorithms enforce in a distributed database system?

<p>Concurrency control algorithms enforce the isolation property so that concurrent transactions see a consistent database state and leave the database in a consistent state.</p> Signup and view all the answers

What property do reliability measures enforce in distributed database systems?

<p>Reliability measures enforce atomicity and durability.</p> Signup and view all the answers

What is the primary role of data replication in distributed database systems?

<p>The primary role of data replication in distributed database systems is to enhance reliability and availability.</p> Signup and view all the answers

What is the main function of distributed transaction processing in distributed database systems?

<p>The main function of distributed transaction processing is to coordinate transactions that access multiple distributed database nodes.</p> Signup and view all the answers

What is the main purpose of web data management in the context of distributed database systems?

<p>The main purpose of web data management is to manage and process large volumes of data generated from web applications and services.</p> Signup and view all the answers

What is the primary purpose of timestamp-based concurrency control algorithms?

<p>To establish a serialization order and execute transactions accordingly.</p> Signup and view all the answers

How are timestamps assigned to transactions in a distributed DBMS?

<p>Each site autonomously assigns timestamps based on its local counter, appending its own identifier to the counter value.</p> Signup and view all the answers

What does the timestamp consist of in the context of a distributed DBMS?

<p>The timestamp consists of a local counter value and a site identifier.</p> Signup and view all the answers

What is the role of the coordinating Transaction Manager (TM) in the basic timestamp ordering (TO) algorithm?

<p>The coordinating TM assigns timestamps to transactions, determines the storage sites of data items, and sends relevant operations to these sites.</p> Signup and view all the answers

What is the TO Rule in the context of the basic TO algorithm?

<p>According to the TO Rule, a conflicting operation Oij is executed before another conflicting operation Okl if and only if ts(Ti) &lt; ts(Tk).</p> Signup and view all the answers

What property does the basic TO algorithm guarantee in terms of deadlocks?

<p>The basic TO algorithm never causes deadlocks.</p> Signup and view all the answers

How does the basic TO algorithm handle conflicting operations?

<p>The basic TO algorithm checks each new operation against conflicting ones and rejects it if the transaction is younger than all conflicting ones, causing a restart.</p> Signup and view all the answers

What drawback is the conservative TO algorithm designed to mitigate compared to the basic TO algorithm?

<p>The conservative TO algorithm aims to reduce the number of transaction restarts.</p> Signup and view all the answers

How do conservative TO algorithms handle operations in contrast to the basic TO algorithm?

<p>Conservative TO algorithms delay each operation instead of causing immediate restarts.</p> Signup and view all the answers

What is the preferred method for assigning timestamps to transactions in a distributed DBMS?

<p>The preferred method is for each site to autonomously assign timestamps based on its local counter, appending its own identifier to the counter value.</p> Signup and view all the answers

Why does the conservative TO algorithm prioritize delaying operations?

<p>The conservative TO algorithm aims to lower system overhead by reducing the number of transaction restarts.</p> Signup and view all the answers

What drawback does the basic TO algorithm have in terms of transaction restarts?

<p>The basic TO algorithm may potentially cause a transaction to restart numerous times.</p> Signup and view all the answers

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