Transaction management with @Transactional in Spring Boot - Step-by-Step Execution

Concept Flow - Transaction management with @Transactional

Start method call

↓

Check for @Transactional

Yes↓

Open transaction

↓

Execute method code

↓

Method completes?

↓

Commit

↓

Close transaction

↓

Return result

When a method with @Transactional is called, a transaction opens. If the method finishes without error, it commits. If an error occurs, it rolls back.

Execution Sample

Spring Boot

@Transactional
public void transferMoney() {
  debitAccount();
  creditAccount();
}

This method runs inside a transaction. If debit or credit fails, all changes undo.

Execution Table

Step	Action	Transaction State	Method Execution	Result
1	Method transferMoney() called	No transaction	Not started	Waiting
2	Detect @Transactional annotation	No transaction	Preparing to start	Ready to open
3	Open transaction	Transaction open	Start debitAccount()	In progress
4	Execute debitAccount()	Transaction open	Debit successful	Continue
5	Execute creditAccount()	Transaction open	Credit successful	Continue
6	Method completes normally	Transaction open	All steps done	Commit transaction
7	Commit transaction	Transaction committed	End method	Success
8	Return from method	No transaction	Method finished	Result returned

💡 Method finishes without exceptions, so transaction commits and closes.

Variable Tracker

Variable	Start	After Step 3	After Step 6	Final
transactionState	No transaction	Transaction open	Transaction open	Transaction committed
methodExecution	Not started	In progress	All steps done	Finished

Key Moments - 3 Insights

Why does the transaction rollback if an exception occurs inside the method?

Because in the execution_table, if the method does not complete normally (step 6), the transaction manager triggers a rollback instead of commit.

What happens if the method completes without errors?

As shown in step 6 and 7, the transaction commits and then closes, making all changes permanent.

Does the transaction start before or after the method code runs?

The transaction opens before the method code runs, as seen in step 3, ensuring all method actions are inside the transaction.

Visual Quiz - 3 Questions

Look at the execution_table, what is the transaction state at Step 4?

A No transaction

B Transaction open

C Transaction committed

D Transaction rolled back

💡 Hint

Check the 'Transaction State' column at Step 4 in the execution_table.

At which step does the transaction commit?

A Step 7

B Step 6

C Step 5

D Step 8

💡 Hint

Look for the 'Commit transaction' action in the execution_table.

If debitAccount() throws an exception, what would happen to the transaction?

A Transaction stays open

B Transaction commits anyway

C Transaction rolls back

D Transaction closes without commit or rollback

💡 Hint

Recall that if the method does not complete normally, the transaction manager rolls back (see key_moments).

Concept Snapshot

@Transactional annotation wraps method in a transaction.
Transaction opens before method runs.
If method finishes normally, transaction commits.
If method throws exception, transaction rolls back.
Ensures all-or-nothing changes for data consistency.

Full Transcript

When you call a method marked with @Transactional, Spring opens a transaction before running the method code. Inside the method, all database changes happen within this transaction. If the method finishes without errors, Spring commits the transaction, making all changes permanent. But if an error happens, Spring rolls back the transaction, undoing all changes to keep data safe. This way, @Transactional helps keep your data consistent by making sure either all steps succeed or none do.