Question

Howto declare @Entity class for oracle table w/o PK?

I has received the error message:
Column “rowid” cannot be resolved on table “LOG”

when doing mapping like this:

@Entity
public class Log implements Serializable {
…
@Id
private ROWID rowid;
…
}

Answer 1

Howto declare @Entity class for oracle table w/o PK?

Mapping a ROWID as Id isn’t supported by standard JPA and I couldn’t find any obvious proof that EclipseLink is providing an extension for this (I only found this message).

But this is not your only option and the JPA wikibook has a good paragraph about this situation:

No Primary Key

Sometimes your object or table has no
primary key. The best solution in this
case is normally to add a generated id
to the object and table. If you do not
have this option, sometimes there is a
column or set of columns in the table
that make up a unique value. You can
use this unique set of columns as your
id in JPA. The JPA Id does not
always have to match the database
table primary key constraint, nor is a
primary key or a unique constraint
required.

If your table truly has no unique
columns, then use all of the columns
as the id. Typically when this occurs
the data is read-only, so even if the
table allows duplicate rows with the
same values, the objects will be the
same anyway, so it does not matter
that JPA thinks they are the same
object. The issue with allowing
updates and deletes is that there is
no way to uniquely identify the
object’s row, so all of the matching
rows will be updated or deleted.

If your object does not have an id,
but its’ table does, this is fine.
Make the object and Embeddable
object, embeddable objects do not have
ids. You will need a Entity that
contains this Embeddable to persist
and query it.