What is the role of the 'rollback' statement in transaction management?
- Committing the changes made by the current transaction
- Ending the current transaction
- Initiating a new transaction
- Reversing the changes made by the current transaction
The 'rollback' statement in transaction management is used to undo the changes made by the current transaction. If an error occurs or a condition is met, the 'rollback' command ensures that all changes made so far in the transaction are rolled back, maintaining data consistency.
What is the difference between 'dirty read' and 'non-repeatable read' in the context of transaction isolation levels?
- Dirty read: Reading committed data
- Dirty read: Reading uncommitted data
- Non-repeatable read: Reading committed data
- Non-repeatable read: Reading uncommitted data
In the context of transaction isolation levels, a 'dirty read' occurs when a transaction reads uncommitted data from another transaction, while a 'non-repeatable read' happens when a transaction reads data committed by another transaction but the data changes before the first transaction completes. Understanding these concepts is crucial in managing data consistency and isolation in concurrent transactions.
How do distributed transactions differ from local transactions?
- Concurrency and Durability
- Consistency and Recovery
- Isolation and Atomicity
- Scope and Participants
Distributed transactions involve multiple participants and a wider scope, whereas local transactions are limited to a single resource or database.
What is two-phase commit protocol in the context of transaction management?
- A protocol for authentication
- A protocol for coordination
- A protocol for data retrieval
- A protocol for voting
The two-phase commit protocol is a coordination protocol involving a voting phase and a decision phase to ensure distributed transaction consistency.
How do savepoints work within a transaction?
- Allow for partial rollback
- Commit the entire transaction
- Isolate a transaction
- Terminate the transaction
Savepoints allow for partial rollback within a transaction, providing a way to undo part of the transaction without affecting the entire operation.
In SQL, the command ________ is used to permanently save changes made by the current transaction.
- BEGIN TRANSACTION
- COMMIT
- ROLLBACK
- SAVEPOINT
The COMMIT command in SQL is used to permanently save changes made by the current transaction.
The ability of a transaction to operate independently of other transactions is known as __________.
- Atomicity
- Consistency
- Durability
- Isolation
The ability of a transaction to operate independently of other transactions is known as Isolation.
A transaction's property ensuring that either all its operations are completed successfully, or none are, is known as _________.
- Atomicity
- Consistency
- Durability
- Isolation
A transaction's property ensuring that either all its operations are completed successfully, or none are, is known as Atomicity.
A transaction in a financial application requires updating multiple accounts. If one update fails, what should happen to ensure data consistency?
- Commit the successful updates
- Ignore the failed update and proceed
- Log the failure and retry the update
- Rollback the entire transaction
In a financial application, to ensure data consistency, it's crucial to rollback the entire transaction if any update within it fails. This helps maintain the integrity of the financial data.
In transaction management, what does the term 'ACID' stand for?
- Advanced Commitment Integration Design
- All Committed in Database
- Association of Commitment in Databases
- Atomicity, Consistency, Isolation, Durability
'ACID' stands for Atomicity, Consistency, Isolation, and Durability, which are the key properties ensuring reliable and secure database transactions.