6.4

Atomic Transactions

Transactions that ensure partial results are not saved, maintaining database integrity.

Rollback

A process that reverses changes made during a transaction in case of errors or failures.

Durable Transactions

Transactions that are guaranteed to remain committed even in case of hardware or software failures.

Recovery System

A mechanism that manages data integrity through failure scenarios like transaction failures and system failures.

Recovery Log

A file that records database operations and their states during transactions.

Update Record

A record that indicates a transaction has modified data.

Checkpoint Record

A record that indicates all data in main memory has been saved to storage media.

Compensation (Undo) Record

A record that indicates data has been restored to its original value during a rollback.

Start Record

A record that marks the beginning of a transaction in the recovery log.

Redo Phase

The stage in recovery where all actions of completed transactions are 'replayed'.

Active Transaction List

A list of transactions that are in progress within the recovery system.

Cold Backup

A backup technique where the database is copied at checkpoints and recovery reads the log from the checkpoint.

Hot Backup

A backup method that allows transactions to continue executing while log records are sent to a secondary database.

Database Availability

The percentage of time that a database is operational and responsive to applications.

Storage Media Failure

A situation where the database is corrupted or the connection to the database is lost.

Atomicity

A property that ensures that a transaction is treated as a single unit of work, which is either fully completed or not executed at all.

Consistency

Ensures that a database remains in a valid state before and after a transaction, preserving data integrity.

Isolation

A property that ensures that transactions occur independently without interference from one another.

Durability

The assurance that changes from a completed transaction are permanent, even in the event of a failure.

Transaction Log

A file that records all the transactions that have been executed against the database.

Commit

The process of making all changes made in a transaction permanent in the database.

Failure

An event that causes a transaction to be unable to complete.

Concurrency Control

Mechanisms used to ensure that transactions are executed in a safe and isolated manner.

Data Integrity

The maintenance of accurate and consistent data over its entire lifecycle.

System Recovery

The process of restoring a system to a functional state after a failure.