InheritanceType.TABLE_PER_CLASS broken in JBoss5 CR2?

[wolfgangknauf]

I have a sample with entity inheritance (by the way: just a sample to show inheritance, nothing which makes sense ;-) ): one base class (ZutatBaseInheritanceBean with generated id and one field), three child classes (ZutatGewichtInheritanceBean, ZutatFluessigkeitInheritanceBean, ZutatStueckzahlInheritanceBean).

I want to make it running in all three inheritance strategies. SINGLE_TABLE und JOINED work fine. But for TABLE_PER_CLASS, it fails to populate a collection of all entities. The first type (ZutatGewichtInheritanceBean) is properly initialized, the other two types just contain the base class fields, all their individual fields are empty.

The named query to load all types of child entities is:

@NamedQuery (name="findAllZutaten", query="select o from ZutatBaseInheritanceBean o")

This seems to be a matter of the SQL statement which I see in the console:

select zutatbasei0_.id as id113_, zutatbasei0_.kuchen_id as kuchen3_113_, zutatbasei0_.zutatName as zutatName113_,
zutatbasei0_.gewicht as gewicht114_, zutatbasei0_.gewichtEinheit as gewichtE2_114_,
zutatbasei0_.masseinheit as masseinh1_115_, zutatbasei0_.masseinheitMenge as masseinh2_115_,
zutatbasei0_.anzahl as anzahl116_, zutatbasei0_.clazz_ as clazz_ from
( select id, gewicht, zutatName, null as anzahl, kuchen_id, null as masseinheit, gewichtEinheit, null as masseinheitMenge, 1 as clazz_ from ZutatGewichtInheritanceBean union select id, null as gewicht, zutatName, null as anzahl, kuchen_id, masseinheit, null as gewichtEinheit, masseinheitMenge, 2 as clazz_ from ZutatFluessigkeitInheritanceBean union select id, null as gewicht, zutatName, anzahl, kuchen_id, null as masseinheit, null as gewichtEinheit, null as masseinheitMenge, 3 as clazz_ from ZutatStueckzahlInheritanceBean ) zutatbasei0_

The columns from ZutatFluessigkeitInheritanceBean and ZutatStueckzahlInheritanceBean are always NULL, so I suspect that either Hypersonic does not support it or the EntityManager creates a wrong query.

I have a "working" sample at http://www.informatik.fh-wiesbaden.de/~knauf/KomponentenArchitekturen2008/kuchenzutatinheritance/KuchenZutatInheritance.ear, but it is completely in german, and the app client is a bit difficult to start (uses EJB injection), so I hope someone can make sense of my descriptions ;-).

I had a similar sample with two child classes, which worked in JBoss 4.2. If I find the time, I will test it with JBoss 5.

Thanks

Wolfgang

[wolfgangknauf]

Ok, after building a small sample, analyzing the sql and doing some google, I can tell that the sql for Hypersonic is wrong.

Here is a small broken sample: http://www.informatik.fh-wiesbaden.de/~knauf/private/InheritanceTablePerClass.ear
It contains all sources and can be run on JBoss 4.2 and JBoss 5 (broken on both, my earlier statement "my other sample worked in 4.2" was wrong, because I did not access the subclass fields ;-) ).

The sample contains a base entity with three childs, and a web client at "http://localhost:8080/InheritanceTablePerClassWeb/index.jsp", which creates three entities and tries to lookup them.

Now about the sql:
JBoss executes this:

select base0_.id as id56_, base0_.name as name56_, base0_.child3Field as child1_57_,
base0_.child2Field as child1_58_, base0_.child1Field as child1_59_, base0_.clazz_ as clazz_ from
 (select id, null as child2Field, child3Field, null as child1Field, name,
 1 as clazz_ from Child3
 union select id, child2Field, null as child3Field, null as child1Field, name,
 2 as clazz_ from Child2
 union select id, null as child2Field, null as child3Field, child1Field, name,
 3 as clazz_ from Child1 )
base0_

Executing just the inner subselect brings correct results. But the full statement does not work.

This forum post brought me to a solution that brings correct results in HSQL Database Manager: http://kaigrabfelder.de/en/2008/05/19/1211216700000.html

Here is a reworked SQL statement:

select base0_.id as id56_, base0_.name as name56_,
base0_.child3Field as child1_57_, base0_.child2Field as child1_58_,
base0_.child1Field as child1_59_, base0_.clazz_ as clazz_ from
 (select id, cast (null as VARCHAR) as child2Field, child3Field,
 cast (null as VARCHAR) as child1Field, name, 1 as clazz_ from Child3
 union select id, child2Field, cast (null as VARCHAR) as child3Field,
 cast (null as VARCHAR) as child1Field, name, 2 as clazz_ from Child2
 union select id, cast (null as VARCHAR) as child2Field, cast (null as VARCHAR) as child3Field,
 child1Field, name, 3 as clazz_ from Child1 ) base0_

Is this a JBoss bug, or a Hypersonic bug? Is there some workaround (specifying the statement for the join)?
Should I file a JBoss bug?

Thanks

Wolfgang

[alrubinger]

"Wolfgang Knauf" wrote:
Is this a JBoss bug, or a Hypersonic bug? Is there some workaround (specifying the statement for the join)?
Should I file a JBoss bug?

The guys over at Hibernate would be able to better answer this. Over here at EJB3 we hand off to them as our persistence provider.

S,
ALR

[wolfgangknauf]

Done!

http://forum.hibernate.org/viewtopic.php?p=2400024

Wolfgang

[wolfgangknauf]

Seems to be filed in Hibernate JIRA already:
http://opensource.atlassian.com/projects/hibernate/browse/HHH-2920