Spring @Transactional read-only mode rollback behaviour
hibernate, java, postgresql, spring, transactions
Solution
So as far as I understand, you are worried about the roll-back. In this case a `readOnly` is a `select statement` and usually there is nothing to roll-back from a `read`. The only place where this is handy is when you read under a lock and when the transaction finishes you release that lock.
AFAIK `readOnly` will set the flushmode to `FlushMode.NEVER` and that is good and bad at the same time. Good, because there will no dirty checking, as described here. Bad because if you call a read/write transaction within a `readOnly` transaction, the transaction will silently fail to commit because the session is not flushed. This is easily testable btw - and I hope things have not changed since I've tried this.
Then there is the pool of connections. I know that `C3P0`'s default policy is to rollback any uncommitted work. The flag to control this is `autoCommitOnClose`.
Then there is this link about `readOnly` and `postgres` - which I have not worked with and can't really tell my opinion on.
Now to your point about `Transaction rolled back because it has been marked as rollback-only`. For a `readOnly` transaction there might be nothing to roll-back as I said before, so this really depends on how you chain your `@Transactional` methods IMO.
Problem
I have some service layer method with `@Transactional(readOnly=true)` and this method causes some `RuntimeException` quite often (let's say it is some `NotFoundException` exception). I'm using ORM Hibernate also for the DB interaction process. Is it legal pattern to do so? What is the default behaviour in this case in sense of "roll-back" behaviour? Can it influence somehow badly on connections's state or lead to any problems? It isn't something like "why not try it by your self?". I have a suspicion that this could lead to the `Transaction rolled back because it has been marked as rollback-only` error in the same method after some number of exceptions. This could be very specific JDBC PostgreSQL driver error. That is why I'm wondering about this design in general: is it something legal or illegal to do so?