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[CDO] How to proceed when a genmodel changes? [message #1702463]

Wed, 22 July 2015 09:34

Eclipse User

Hi all!

I'm currently collaborating in a project that uses EMF and CDO. The point is we have an environment with an Entity called B (for example). Users have been recording elements in B but now, that entity has a new column.

The question is: if we update the model and launch our server, we get an exception, because the existing database doesn't have the new column... Is there any way in order to keep the data, update the schema and restore back all the data?

At this moment, the weight of our sql dump is about 15GB

Thank you so much in advance!!!

Re: [CDO] How to proceed when a genmodel changes? [message #1702505 is a reply to message #1702463]

Wed, 22 July 2015 14:41

Eclipse User

Am 22.07.2015 um 16:59 schrieb Daniel Alonso:
> Hi all!
>
> I'm currently collaborating in a project that uses EMF and CDO. The point is we have an environment with an Entity
> called B (for example). Users have been recording elements in B but now, that entity has a new column.
>
> The question is: if we update the model and launch our server, we get an exception, because the existing database
> doesn't have the new column... Is there any way in order to keep the data, update the schema and restore back all the
> data?
There are several threads about "model evolution" in this forum that you should read first. You should find a number of
approaches there. The preferred one involves CDOServerExporter, external migration of the XML export and CDOServerImporter.

Cheers
/Eike

----
http://www.esc-net.de
http://thegordian.blogspot.com
http://twitter.com/eikestepper

>
> At this moment, the weight of our sql dump is about 15GB
>
> Thank you so much in advance!!!

Re: [CDO] How to proceed when a genmodel changes? [message #1702516 is a reply to message #1702505]

Wed, 22 July 2015 15:35

Eclipse User

I will also mention, that given that the case you're migrated, you scenario seems pretty simple.
1. Make sure you're using DBStore Annotations - to know table and columns names for sure (CDO will sometimes use object id's to name tables)
2. Write simple DDL to add a column of corresponding type to you database.
3. (Most important step!) is to update model stored in CDO. For this, you will need to perform a binary export of you model (see org.eclipse.emf.cdo.common.model.EMFUtil.getEPackageBytes(ePackage, zipped, packageRegistry), zipped should be true. Then you will need to upload the resulting BLOB in CDO_PACKAGE_UNIT table.

There is some more difficulties to that process, like making inserts to CDO_EXTERNAL_REFS when adding a new class - or crearing a table for many-to-many references but in general, most cases of backwards-compatible model evolution should be doable.

Re: [CDO] How to proceed when a genmodel changes? [message #1702567 is a reply to message #1702516]

Thu, 23 July 2015 05:53

Eclipse User

Thanks to all!

At this moment, we have found that this issue is happening

https://bugs.eclipse.org/bugs/show_bug.cgi?id=343417

'cause still we are using cdo 4.1

According to your posts, still there is no automagically solution, right?

Re: [CDO] How to proceed when a genmodel changes? [message #1702575 is a reply to message #1702567]

Thu, 23 July 2015 07:44

Eclipse User

Am 23.07.2015 um 11:53 schrieb Daniel Alonso:
> Thanks to all!
>
> At this moment, we have found that this issue is happening
>
> https://bugs.eclipse.org/bugs/show_bug.cgi?id=343417
>
> 'cause still we are using cdo 4.1
>
> According to your posts, still there is no automagically solution, right?
You should definitely try to upgrade to newest/newer CDO versions. CDO 4.4 has just been released.

Cheers
/Eike

----
http://www.esc-net.de
http://thegordian.blogspot.com
http://twitter.com/eikestepper

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