Distributed Database Systems Quiz 2 Solution

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Questions and Answers

What is the main focus of Distributed Database Systems?

Query Processing and optimization

Data Replication

Web Data Management

Introduction to Distributed Database (correct)

What does a transaction in a database consist of?

A series of random events

A single action

A collection of actions preserving system consistency (correct)

A unit of unreliable computation

What does the Commit operation ensure in a transaction?

The updates made by the transaction are permanent (correct)

The transaction is paused

The transaction is aborted

The database is rolled back

What is the primary concern of Transaction Management?

Ensuring database integrity Signup and view all the answers

What is the nature of a distributed database transaction?

A unit of consistent and reliable computation Signup and view all the answers

What does Concurrency transparency in a transaction ensure?

Visibility of intermediate transaction states Signup and view all the answers

What is the function of the Abort operation in a database transaction?

Undo the transaction’s actions, making it as if the transaction has never been executed Signup and view all the answers

What does the read set of a transaction include?

Data items that it reads Signup and view all the answers

Which property of a transaction ensures that all its writes are committed before it completes all its writes?

Atomicity Signup and view all the answers

What does Degree 3 of consistency entail for a transaction?

Other transactions do not dirty any data read by T before T completes Signup and view all the answers

Which isolation level allows for fuzzy reads and phantoms, but not dirty reads?

Read Committed Signup and view all the answers

What does it mean for a database to be in a consistent state?

It obeys all of the consistency (integrity) constraints defined over it Signup and view all the answers

What does transaction consistency refer to?

The operations of concurrent transactions Signup and view all the answers

What do concurrency control algorithms enforce?

The isolation property so that concurrent transactions see a consistent database state Signup and view all the answers

What does reliability refer to in the context of a system?

Tolerance of system failures and ability to provide services even when failures occur Signup and view all the answers

What is the primary focus of recoverable DBMS?

Moving forward to a new consistent state following various types of failures Signup and view all the answers

Study Notes

Distributed Database Systems

The main focus of Distributed Database Systems is to manage and store data across multiple physical locations.

Transactions

A transaction in a database consists of a sequence of operations executed as a single, all-or-nothing unit of work.
The Commit operation ensures that all changes made by a transaction are written to the database and made permanent.

Transaction Management

The primary concern of Transaction Management is to ensure that database transactions are executed reliably and securely.

Distributed Database Transactions

A distributed database transaction is a transaction that accesses data from multiple databases or nodes.

Concurrency Transparency

Concurrency transparency in a transaction ensures that the transaction executes as if it were the only transaction operating on the database.

Abort Operation

The Abort operation in a database transaction rolls back all changes made by the transaction and returns the database to its previous state.

Transaction Read Set

The read set of a transaction includes all the data items that the transaction reads during its execution.

Transaction Properties

The property of a transaction that ensures all its writes are committed before it completes all its writes is called Atomicity.
Degree 3 of consistency entails that a transaction ensures that all its writes are committed before it completes all its reads.

Isolation Levels

The isolation level that allows for fuzzy reads and phantoms, but not dirty reads, is called Repeatable Read.

Database Consistency

For a database to be in a consistent state means that the data is valid and adheres to the database's constraints and rules.
Transaction consistency refers to the assurance that the transaction maintains the database's consistency.

Concurrency Control

Concurrency control algorithms enforce rules to ensure that multiple transactions execute concurrently without conflicts.

System Reliability

Reliability refers to the ability of a system to continue operating correctly even in the presence of failures or errors.

Recoverable DBMS

The primary focus of a recoverable DBMS is to ensure that the database can recover from failures or errors without losing data or compromising consistency.

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Description

Test your knowledge of distributed database systems with this quiz that covers topics like distributed database design, query processing, distributed transaction processing, concurrency control, reliability, data replication, big data processing, and web data management.