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

[Paul Benedict (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-3414?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=33735#action_33735 ] 

Paul Benedict commented on HHH-3414:
------------------------------------

Fetch profiles aren't a necessity, but it is one solution to the problem. One issue that I have with Hibernate is that Criteria and HQL allow queries to be more eagerly in their fetch strategies (setFetchMode), but you can't relax it. Once something is mapped as eager, it cannot be undone. This is where the deprecated FetchMode.LAZY could make a nice return.

> fetch profiles
> --------------
>
>                 Key: HHH-3414
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-3414
>             Project: Hibernate Core
>          Issue Type: New Feature
>          Components: core, metamodel
>            Reporter: Steve Ebersole
>            Assignee: Steve Ebersole
>             Fix For: 3.7
>
>
> 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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