[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-2035) Generate hibernate.cfg file from used persisted entities only

[Holger Haag (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-2035?page=comments#action_24210 ] 

Holger Haag commented on HHH-2035:
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Hi,

thanks for your time.

1) Where are the code that actual add elements to the usedPersisters map ?

sorry, that was a mistake when I created the patch. I'll provide a new patch anyway.

2) Does it work with associations ? (e..g if A point to B and only A is used, B is still needed in your configuration)

the new patch should... The entities are now collected in AbstractEntityPersister, which seems to be a better place (the old patch used TwoPhaseLoad).

I've tried the following scenarios
- simple class mapping (1 class = 1 table)
- simple one-to-many (foreign key) relationship
- insert new objects
- search for existing objects

Not sure about other scenarios which I do not use though (e.g. many-to-many or collections). 

3) Couldn't this be done via eventlisteners instead of mutating TwoPhaseLoad class? 

I'll leave the answer up to you ;-) Since I'm not that familiar with the hibernate code, I've used a very simple approach. But I cannot help you on this issue very much. 

I also haven't looked very much at performance or thread synchronization issues, since I assume that calls to java.util.HashMap are pretty fast and even if two threads add the same entity simultaneously, that shouldn't be a big issue.

Please note that the new patch now  has a new class - org.hibernate.stat.PersistedEntities - which covers most of the required functions. The patch to the AbstractEntityPersister only contains one call to PersistedEntities. That should make it easier for you if you want  to use a different approach, e.g. the above mentioned listeners.




> Generate hibernate.cfg file from used persisted entities only
> -------------------------------------------------------------
>
>          Key: HHH-2035
>          URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2035
>      Project: Hibernate3
>         Type: New Feature

>   Components: core
>  Environment: Hibernate 3.x + Hibernate annotations
>     Reporter: Holger Haag
>     Priority: Minor
>  Attachments: TwoPhaseLoad-writeUsedPersisters.patch, hibernate-template.cfg.xml
>
>
> Original post from Hibernate forum: http://forum.hibernate.org/viewtopic.php?t=963888
> The patch allows to call a new method TwoPhaseLoad.writeUsedPersisters which will generate a complete hibernate.cfg configuration file containing only the entities which have been persisted so far. 
> The rationale behind this is that for unit test cases it is often sufficient - and much faster - to initialize hibernate with only a subset of all persisted classes, but it is cumbersome to find out which subset is the smallest possible.
> Attached is a SVN patch for the latest SVN trunk and a sample template file.
> Feel free to modify/put it into the hibernate code in any way you want, I think it can increase productivity - startup times for my test cases have dropped by 10 seconds.
> Please note that this patch will only work if you use Hibernate annotations since the generated XML file only contains class, not column mappings.

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