Transaction.setIsolation()

[gavinking]

@Sanne has pointed out that it's currently quite inconvenient to change the transaction isolation level, even though JDBC has an API for that.

I think it should be relatively straightforward to add a setIsolation() method to the Transaction interface.

WDYT?

[sebersole]

Actually from what I can tell, in JTA environments you generally cannot set isolation level per Connection as this is something managed at the DataSource level. I'm not very keen on exposing this if we cannot support it consistently.

One option is to simply set the isolation on the underlying Connection regardless of local or JTA transactions and let the user deal with the ramifications (inconsistent).

Another option would be to restrict this to just local transaction use cases.

Another consideration is how to handle this for databases which do not support certain isolations.

I guess the elephant in the room is what kind of guarantees we we envision here

[gavinking]

I thought Stuart told us it's possible in Wildfly, even if not according to the spec.

[Sanne]

Right, I've certainly used it in the past on older JBoss AS versions. But I'm not sure how this would look in latest WildFly.

[beikov]

I can tell you, that back when I was a Hibernate user, I wanted to switch to SERIALIZABLE for certain transactions, so it definitely is something that might be interesting to some users. AFAIU, the only "standard" way to implement such a use case, is to create 2 data sources and 2 persistence units, which increases memory pressure.

[gavinking]

Yeah I mean I think it's clear that's a shit solution.

[scottmarlow]

https://vladmihalcea.com/a-beginners-guide-to-transaction-isolation-levels-in-enterprise-java/ was a good refresher for myself, mentioning it here for others that might like a refresher.

I have feedback on this topic and will share it soon.