[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-2235) Support for null map-keys in <map> mappings

[Ulf gohde (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-2235?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_27264 ] 

Ulf gohde commented on HHH-2235:
--------------------------------

yep, you are right about the origin of the term relational.

With the "stuff the oracle provides" you mean tables without PK and with compound unique constraint that allows null values? 

That is not just oracle, you can do exactly the same in SQL Server. Not sure about the latest mysql version but it definitely worked in one of the older versions. 

The only database I know of that is not allowing null values in unique constaints is DB2 on windows. But DB2 on windows is not even supporting ALTER TABLE DROP COLUMN which means it is not even SQL-92 compliant.

> Support for null map-keys in <map> mappings
> -------------------------------------------
>
>                 Key: HHH-2235
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2235
>             Project: Hibernate3
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 3.2.0.ga
>            Reporter: Igor Lobanov
>            Priority: Minor
>
> I'm not sure if I should file it as a bug.
> Hibernate requires index column for <map> mappings to be not null. This is required by the code in AbstractCollectionPersister#readIndex(...), which raises exception if index column is null. However, when I override collection persister and force readIndex method to return null, everything seems to work fine. Hibernate allows me to work with maps using null value as a key. Though I havn't tested it extensivly yet.
> What is the reason for disallowing null values as a keys? If there are possible complicated error conditions, then this issue is a feature request for null-values support for <map> mappings. If there are no errors possible, then constraining such behavior is probably wrong. 

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