[hibernate-dev] Fwd: Sub entities and Multi-version support

[Steve Ebersole]

Maybe we should just go "all the way" and have a per-column version? ;)

Anyway, like I said...

Personally I am inclined to vote -1 to this at the moment,  but I am
interested to hear what others might think.

On Wed, Nov 18, 2015 at 11:35 PM Vlad Mihalcea <mihalcea.vlad at gmail.com>
wrote:

> Actually both merge() and update() can still cause a "write skew"
> phenomena, especially when using dynamic updates + OptimisticLockType DIRTY
> <
> https://docs.jboss.org/hibernate/orm/4.3/javadocs/org/hibernate/annotations/OptimisticLockType.html#DIRTY
> >
> or OptimisticLockType ALL
> <
> https://docs.jboss.org/hibernate/orm/4.3/javadocs/org/hibernate/annotations/OptimisticLockType.html#ALL
> >
> .
> Let's say I have an imaginary Product entity with a price and a quantity,
> and when I "purchase" it, I simply decrease its quantity (considering that
> the price doesn't change).
>
> 1. I load the Product with price 9.99 and quantity 5 in one Hibernate
> Session/HTTP request
> 2. Bob comes and changes the price to 14.99
> 3. I go back to place my order and I will use merge(). I will load the
> Product with the new price but I won't be aware of that, and I'll issue a
> dynamic-update on quantity, by simply decreasing.
>
> This anomaly can currently be fixed by @Version implementation. Neither
> DIRTY or ALL can detect this anomaly, because they relate to the latest
> state (Bob's change) and not what I used to see in my first transaction.
> That's how sub-versions would fix this because, by grouping properties
> joined by a business transaction rule (price-quantity-discount), we could
> eliminate conflicts between distinct groups of properties and only raise an
> optimistic locking exception when a property is changed within the same
> group (price-quantity-discount).
>
> If we don't even consider something like this, we can still split the
> tables into smaller ones to achieve the same goal.
>
> Vlad
> _______________________________________________
> hibernate-dev mailing list
> hibernate-dev at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/hibernate-dev
>