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Bug 311069

Summary:	[Hibernate] Mappings with version column are fragile
Product:	[Modeling] EMF	Reporter:	Aleksander Bandelj <aleksander.bandelj>
Component:	cdo.core	Assignee:	Martin Taal <mtaal>
Status:	CLOSED FIXED	QA Contact:
Severity:	normal
Priority:	P3	CC:	mtaal, stepper
Version:	4.2
Target Milestone:	---
Hardware:	PC
OS:	Linux
Whiteboard:

Description Aleksander Bandelj

2010-04-29 13:18:08 EDT

Build Identifier: 

If model has version columns, there are frequent "row was already updated or deleted by other transaction" errors. I suspect there are race conditions and clashes between Hibernate and CDO versioning. Without version columns, everything works OK.

Reproducible: Sometimes

Steps to Reproduce:
Extending org.eclipse.emf.cdo.examples.company model with version column would probably expose most of these bugs

Comment 1 Aleksander Bandelj

2010-04-30 08:04:46 EDT

I've discovered that CDO/Teneo adds always_version if not present. So, example model (and every model) is versioned. Actually, proper working of CDO/Teneo depends on versioning being present, as I discovered in HibernateStoreAccessor#write:

      // first decrease the version for all dirty objects
      // hibernate will increase it again
      for (CDORevision revision : context.getDirtyObjects())
      {
        if (revision instanceof InternalCDORevision)
        {
          InternalCDORevision internalRevision = (InternalCDORevision)revision;
          internalRevision.setVersion(internalRevision.getVersion() - 1);
        }
      }

So, I'm closing this bug.

Comment 2 Martin Taal

2010-04-30 09:07:48 EDT

Re-opening the issue as it warrants some more study (and an update of the wiki).

gr. Martin

Comment 3 Aleksander Bandelj

2010-04-30 10:16:40 EDT

For the time being, I would put two notes in the CDO/Teneo store wiki:

- annotated version attribute in ecore model seems to break things
- always_version is set for you (if not set explicity) and you should never it to false

Comment 4 Martin Taal

2010-05-01 03:56:21 EDT

Remark from Eike in the newsgroup:
I'm not so sure whether modeled version attributes are a good idea. How can we ensure that their values are confirming to CDO's interpretation?

And if you want to exclude certain things (like modeled versions) I think it's better to write code that enforces the rule, not just docs ;-) 

gr. Martin

Comment 5 Martin Taal

2010-05-01 04:07:07 EDT

Aleksander can you change the description to use the prefix: [Hibernate]? Then it will show up in the right list for me.

gr. Martin

Comment 6 Eike Stepper

2010-05-01 04:24:51 EDT

;-)

Comment 7 Martin Taal

2010-05-01 04:26:55 EDT

ha the edit link next to the description, sometimes live is soooo simple (only if I would see it) :-)

Comment 8 Eike Stepper

2012-06-05 07:31:16 EDT

Moving all open bug reports to 4.1 because the release is very near and it's hghly unlikely that there will be spare time to address 4.0 problems.

Please make sure that your patches can be applied against the master branch and that your problem is not already fixed there!!!

Comment 9 Eike Stepper

2012-08-14 22:58:21 EDT

Moving all open issues to 4.2. Open bugs can be ported to 4.1 maintenance after they've been fixed in master.

Comment 10 Martin Taal

2012-11-24 08:59:08 EST

Modeled version attributes are not supported in the CDO Hibernate Store. I pushed several changes to let optimistic locking work correctly using the CDO version number. This is available in the next build.

Comment 11 Eike Stepper

2013-05-20 03:17:49 EDT

Mass update. Don't worry if this bug is already closed!