[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-2309) fetch only the lazy property needed

[nikita tovstoles (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-2309?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=33239#action_33239 ] 

nikita tovstoles commented on HHH-2309:
---------------------------------------

Patch Submission

Attached HHH-2309-nikitaAtDoppelgangerDotCom-version1.patch fixes this issue for the case when all lazy properties are one-to-one's on a shared PK. in this case AbstractEntityPersister.initializeLazyProperty:
-no longer needlessly goes to the 2nd level cache
-initializes requested property only
-Fully passes Hibernate Core testsuite

This patch is based on Hibernate Core 3.3.1.GA and should be applied from within the parent directory of 'core' and 'testsuite' dirs. 

What about the general case? 

I think the only thing(s) left to do to enable un-batched lazy property initialization for cases other than one-to-one on a shared PK are:
- generate appropriate sql lazySelectString given property being requested (in AEP.initializeLazyPropertiesFromDatastore)
- possibly alter CacheEntry to enumerate uninitialized properties (rather than simply store a boolean value)
That's it

Impl Notes

-bulk of work invloved replacing calls to AbstractEntityPersister.hasUninitializedLazyProperties() with ones to a new AbstractEntityPersister.getUninitializedLazyPropertyNames() 

-generates appropriate SQL in AbstractEntityPersister.update (see comments around line 2655)

-made an assumption that StandardPropertyName.getName() returns the same string as in AbstractFieldInterceptor.uninitializedFields (i.e. fieldName == property name). This assumption seems safe because it's already been made in PojoEntityTuplizer.afterInitialize() where lazyProps are being passed in for FieldInterceptionHelper.injectFieldInterceptor(..,..,uninitializedFieldNames)

-left AbstractEntityPersister.generateLazySelectString() unchanged, and so AEP.initializeLazyPropertiesFromDatastore() will execute the same sql as before when lazySelect != null. (that is when lazy props include columns other than shared PKs) Implications: initializeLazyPropertiesFromDatastore will be called every time as long as hasUninitializedLazyProperties will keep returning true





> fetch only the lazy property needed 
> ------------------------------------
>
>                 Key: HHH-2309
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2309
>             Project: Hibernate Core
>          Issue Type: New Feature
>          Components: core
>    Affects Versions: 3.2.1
>            Reporter: German de la Cruz
>         Attachments: HHH-2309-nikitaAtDoppelgangerDotCom-version1.patch
>
>
> The method AbstractEntityPersister.initializeLazyProperty(..) load all lazy properties when it's called. It would be great if could only load the requested property.
> I think the only change we need is in AbstractEntityPersister.initializeLazyPropertiesFromDatastore(...) and AbstractEntityPersister.initializeLazyPropertiesFromCache(...). We must change them in a way that only the referenced property is loaded.
> After that, we must change AbstractFieldInterceptor.intercept(..) to update in a better way the unitializedFields collection (I mean, removing the actual property only instead of null it).
> Besides. Why in line 777 to 780 a query is executed? I think it isn't necessary.
> Thanks.

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