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Transaction Management in Spring Boot

Question:

Do you have experience with transaction management in Spring Boot?

Please explain:

1: What is transaction propagation?

2: What is transaction isolation?

3: What are the different propagation and isolation levels?

How are they used with the @Transactional annotation?

Transaction Management in Spring Boot

1: What is transaction propagation?

Propagation defines how transactions behave when one transactional method calls another. It decides if the called method should run in the same transaction or start a new one.

2: What is transaction isolation?

Isolation controls how one transaction sees data changes made by other transactions. It prevents problems like dirty reads, non-repeatable reads, and phantom reads.

3: Different propagation levels

REQUIRED: Uses current transaction or creates a new one if none exists (default).

REQUIRES_NEW: Always starts a new transaction, suspending the current one.

SUPPORTS: Uses current transaction if exists, else runs non-transactional.

NOT_SUPPORTED: Runs non-transactional, suspends any existing transaction.

MANDATORY: Must run within an existing transaction; throws error if none.

NEVER: Must NOT run within a transaction; throws error if one exists.

NESTED: Runs within a nested transaction if current exists.

4: Different isolation levels

DEFAULT: Uses database default.

READ_UNCOMMITTED: Can see uncommitted changes (least safe).

READ_COMMITTED: Only sees committed changes.

REPEATABLE_READ: Same data for repeated reads in a transaction.

SERIALIZABLE: Highest isolation; transactions run one after another.

5: Using @Transactional annotation

You can set propagation and isolation like this:

@Transactional(
    propagation = Propagation.REQUIRED,
    isolation = Isolation.READ_COMMITTED
)
public void yourMethod() {
    // business logic
}

Summary:

1: Propagation: Controls transaction flow between methods.

2: Isolation: Controls data visibility between transactions.

3: @Transactional: Lets you set both using simple attributes.