What is @Transactional propagation REQUIRED?
PICTURE THIS: SQL JOIN
Left tableKeep these rows
Match keyuser_id = id
Right tableINNER drops misses
Simple meaning
Join an existing transaction or create one.
WHY — Spring instead of guessing?
Why interviewers care about Spring:
Spring questions separate people
who only read docs from people who shipped.
Keep it short, concrete,
and tied to Backend work.
Stay structured
Name the idea, why it exists, then one short example.
Close cleanly
End with when you use it and one common pitfall.
STEPS — What happens step by step?
Before you speak the answer, walk the interviewer through these steps:
- 1Join an existing transaction
or create one.
- 2Nested services share the
same unit of work.
- 3I know REQUIRES_NEW for
separate commits.
- 4Give an example
One tiny concrete case you can say aloud.
- 5Common mistake
What juniors usually get wrong.
- 6Close
When you pick this over the alternative.
EXAMPLE — See it in action
Here's a short line you can speak, broken into clear beats:
Say this line
“Nested services share the same unit of work.”
Break into beats
Nestedservicessharethesameunit
Speaking order
2987408337471632900
Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.
Key takeaway
Join an existing transaction or create one. Nested services share the same unit of work.