[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-3414) fetch profiles

[Gary Sargent (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-3414?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=31126#action_31126 ] 

Gary Sargent commented on HHH-3414:
-----------------------------------

It would be nice to be able to do be able to control things at this level too for formula based properties. These can contain expensive SQL queries and it would be nice to be able to set the fetch mode on such a lazy formula property so it is either retrieved via select (n+1) or fetched non-lazily (equivalent to join).

You could then enable these expensive formula properties only when needed.


> fetch profiles
> --------------
>
>                 Key: HHH-3414
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-3414
>             Project: Hibernate3
>          Issue Type: New Feature
>          Components: core, metamodel
>            Reporter: Steve Ebersole
>            Assignee: Steve Ebersole
>             Fix For: 3.4
>
>
> The concept of fetch profiles as we are discussing here is basically to allow users to dynamically affect the mapped fetching strategy for associations at runtime.
> Consider the following example:
> <class name="Person">
>     ...
>     <set name="addresses" lazy="true" fetch="subselect" ...>
>         ...
>     </set>
> </class>
> <class name="Address">
>     ...
> </class>
> This follows the normal recommendation to map associations as lazy and use a dynamic fetching strategy (ala HQL/Criteria) to modify this lazy behavior at runtime.
> The fetaure discussed here would allow the same behavior for loading as well:
> <hibernate-mapping>
>     <fetch-profile name="person-details">
>         <fetch path="Person.addresses" style="join"/>
>     </fetch-profile>
> </hibernate-mapping>
> Or:
> <hibernate-mapping>
> <class name="Person">
>     ...
>     <fetch-profile name="person-details">
>         <fetch path="addresses" style="join"/>
>     </fetch-profile>
>     <set name="addresses" lazy="true" fetch="subselect" ...>
>         ...
>     </set>
> </class>
> </hibernate-mapping>
> Now, doing:
> session.enableFetchProfile( "person-details" ).get( Person.class, 1 )...
> will load Person#1 as well as their addresses in a single joined query.

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