Spring Boot Transaction Management Concepts 3 — Questions and Answers
Question 1: What does the NESTED propagation behavior do when there is an existing transaction?
- Creates a completely independent new transaction
- Uses a savepoint within the existing transaction allowing partial rollback (Correct answer)
- Joins the existing transaction with no isolation
- Throws an exception indicating nesting is not allowed
Correct answer: Uses a savepoint within the existing transaction allowing partial rollback
NESTED creates a savepoint within the existing transaction so the nested operation can be rolled back independently without affecting the outer transaction.
Question 2: When using Spring Boot with Spring Data JPA, which transaction manager is auto-configured?
- DataSourceTransactionManager
- JtaTransactionManager
- JpaTransactionManager (Correct answer)
- ChainedTransactionManager
Correct answer: JpaTransactionManager
Spring Boot auto-configures JpaTransactionManager when spring-data-jpa is on the classpath and an EntityManagerFactory is present.
Question 3: What is a 'phantom read' in database transactions?
- Reading a row that was deleted in the same transaction
- A query returning different sets of rows due to inserts by another concurrent transaction (Correct answer)
- Reading the same row twice and getting different values
- A read that fails due to a network partition
Correct answer: A query returning different sets of rows due to inserts by another concurrent transaction
A phantom read happens when a transaction re-executes a range query and sees new rows inserted by another committed transaction.
Question 4: How can you configure @Transactional to roll back on a specific checked exception?
- Use rollbackOn = CheckedException.class
- Use rollbackFor = CheckedException.class (Correct answer)
- Wrap the checked exception in a RuntimeException first
- Override the DefaultRollbackRule in TransactionInterceptor
Correct answer: Use rollbackFor = CheckedException.class
The rollbackFor attribute accepts exception classes and instructs Spring to roll back the transaction when those exceptions are thrown.
Question 5: Which isolation level prevents dirty reads and non-repeatable reads but still allows phantom reads?
- READ_UNCOMMITTED
- READ_COMMITTED
- REPEATABLE_READ (Correct answer)
- SERIALIZABLE
Correct answer: REPEATABLE_READ
REPEATABLE_READ prevents dirty and non-repeatable reads by locking read rows, but does not prevent phantom reads from new row insertions.
Question 6: What is the purpose of the MANDATORY propagation behavior?
- Forces Spring to always create a new transaction
- Requires an existing transaction and throws an exception if none exists (Correct answer)
- Makes transaction participation optional
- Marks the method as requiring distributed transaction support
Correct answer: Requires an existing transaction and throws an exception if none exists
MANDATORY propagation requires an active transaction to already exist; if none is found, Spring throws an IllegalTransactionStateException.
Question 7: In Spring, what class is commonly used as the superclass for custom application exceptions that should NOT trigger rollback?
- RuntimeException
- Exception (checked) (Correct answer)
- TransactionException
- DataAccessException
Correct answer: Exception (checked)
Checked exceptions (extending Exception) do not trigger rollback by default in Spring, making them suitable for business exceptions that should allow commit.
Spring Boot Transaction Management Concepts 3
What does the NESTED propagation behavior do when there is an existing transaction?