Re: [hibernate-dev] Feature for handling getNextValue work in same transaction.
Hi Scott,
To the database the sequence of statements will be as follows. The
statements around the read and write of sequence table are an example to
put the sequence_table work into context.
tx1 BEGIN
SELECT blah
SELECT blah
UPDATE blah
SELECT * from sequence_table;
UPDATE sequence_table SET ids=?;
INSERT INTO blah
UPDATE blah
tx1 END
tx1 COMMIT
The work will not be isolated from the current transaction tx1.
Concurrently running transactions will see the changes to sequence_table
depending on the isolation level set when the pool is filled.
Regards,
Jeremy
On 09/08/13 18:20, Scott Marlow wrote:
On 08/08/2013 11:21 AM, Jeremy Whiting wrote:
> Hi,
> I am looking for feedback on changes to provide the ability for work
> to be completed in a currently running transaction. For example when a
> TableGenerator or SequenceGenerator is being used for generating unique
> ids. The statements that select then update the db are executed in a
> separate transaction.
>
> There is a jira for this feature.
>
> https://hibernate.atlassian.net/browse/HHH-8429
>
> Attached to the jira is a diagram. See this link
>
https://hibernate.atlassian.net/secure/attachment/19534/hibernate-class-s...
>
>
> This diagram shows what I currently have implemented. It shows the
> existing classes and the new classes shaded in light blue. The methods
> on a new class IsolationAware show how I've re-jigged most the
> implementation from JtaTransaction to it's new ancestor IsolationAware.
> A new concrete implementation of IsolationDelegate will negotiate the
> work to be executed in the same running transaction.
> The structure splits up the factory/transaction/delegate classes into
> two groups. "same transaction" and "separate transaction". This
has only
> been done for JtaTransaction and the same will probably be necessary for
> CMTTransaction as it also uses a separate transaction to complete work.
> That has been left out to keep the diagram simple.
Your talking about making code changes here but I'm not following
exactly how this new features works. I added my questions about this
to the jira. When you respond there or here, could you please also
include how this new feature depends on isolation level (if it
requires a certain isolation level).
>
> The option of using aggregation at the point where implementers of
> TransactionImplementor are instantiated has been considered. Before too
> much effort is expended coding I wondered what others thought is the
> preferred way to implement this feature.
>
> Jeremy
>
> _______________________________________________
> hibernate-dev mailing list
> hibernate-dev(a)lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/hibernate-dev
>
