Hello,
> when one entity bean extends another, does the extending entity bean's
> table include all of the fields of its parents in its own table?
I don't know how this is solved within JBoss, but conceptually you
have three possibilities:
#1 - typed partitioning
the sum of all fields are stored in a base table, having an
additional column defining what kind of object it is: base, or extended.
for instance
BASE
String name
EXTENDED
int age
would result in the table BASE having
oid INTEGER - object identifier
name VARCHAR
age INTEGER
objType INTEGER (or some kind of IDENTIFIER)
#2 - horizontal partitioning
all fields are repeated in each table for the subclasses.
this would result in a table EXTENDED with oid, name and age, and in
a table BASE with oid and name.
#3 - vertical partitioning
only the very fields belonging to the class are stored in the
corresponding table
this would result in a table BASE with oid and name, and in a table
EXTENDED with oid (also referencing BASE(oid)) and age.
> when i deployed 2 entity beans, one extending the other, the extending
> bean's db table had all the fields defined of its parents' table...
then JBoss adopted the horizontal solution...
Regards,
Marc
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