Distributed Database Systems Quiz 2 Solution

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.