[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-2743) NOT NULL columns for "nullable=false" properties not always correct

[Andreas Schildbach (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-2743?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_27598 ] 

Andreas Schildbach commented on HHH-2743:
-----------------------------------------

The limitation is very understandable. However, Hibernate should know about that limitation when creating a schema. "nullable = false" is still very useful for validating the property.


> NOT NULL columns for "nullable=false" properties not always correct
> -------------------------------------------------------------------
>
>                 Key: HHH-2743
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2743
>             Project: Hibernate3
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 3.2.4.sp1
>            Reporter: Andreas Schildbach
>         Attachments: problem.zip
>
>
> When Hibernate creates a schema for a "table-per-class-hierarchy" mapping, it does not take into account that some properties might only exist on single branches of that hierarchy.
> Have a look at the attached example (Maven2: mvn eclipse:eclipse to create an eclipse project).
> Classes A and B extend Base. Class A defines a property "a", and B defines b - both with "nullable = false". Hibernate then creates a "NOT NULL" column for those properties. I think this is not correct, because even if instances of A always have that property set it might still be NULL (for instances of B) in the database due to the table-per-class-hierarchy mapping.
> Here is what happens if you start "ProblemTest":
> "Attempt to insert null into a non-nullable column: column: B table: BASE in statement [insert into Base (id, a, class) values (null, ?, 'a')]"
> This is the schema that has been created by Hibernate for HSQLDB:
> create table Base
> (
>   class varchar(31) not null,
>   id integer generated by default as identity (start with 1),
>   a integer not null,
>   b integer not null,
>   primary key (id)
> )

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