PostgreSQL Inheritance naming issue in Spring boot

Question

I am working on jpa with PostgreSQL, and I got an error that seems very odd. I have the example ddl below. The child tables share the same name with two different data types, and they are inherited with the parent table.

CREATE TABLE Parent
(
    id  VARCHAR(20) NOT NULL
)

CREATE TABLE child1
(
    test       double precision
)
INHERITS (Parent);


CREATE TABLE child2
(
    test       boolean
)
INHERITS (Parent);

For Entity

@Entity
@Table(
    name = "parent",
)
@NamedQuery(
    name = "parent",
    query = "SELECT p FROM Parent p"
)
@Inheritance(
    strategy = InheritanceType.TABLE_PER_CLASS
)
@Data
@NoArgsConstructor
public class Parent implements Serializable {
   @Id
   @NotNull
   @Column(name = "id")
   String id;
}

Child table

@Entity
@Table(
    name = "child1"
)
@NamedQuery(
    name = "child1",
    query = "SELECT c FROM Child1 c"
)
@Data
@NoArgsConstructor
public class Child1 extend Parent {
    @Column(name = test)
    private Double test;
}

Child2 table

@Entity
@Table(
    name = "child2"
)
@NamedQuery(
    name = "child2",
    query = "SELECT c FROM Child2 c"
)
@Data
@NoArgsConstructor
public class Child2 extend Parent {
    @Column(name = test)
    private Boolean test;
}

When I use controller to create a new record on parent entity, it will return error like

ERROR: UNION types double precision and boolean cannot be matched

I know jpa are using union to find the matching result which causing this error. For Joined and SingleTable, they are not working in here since I want the child can have the parent's attributes. Parent will have its own. The table per class was the best choice for me. I am wondering any other way to fix this issue?

Answer 1

Your Child1 and Child2 classes both define an entity attribute with the name test which gets mapped to a database column with the same name. Hibernate can't handle that when you select from both tables in a polymorphic query. You need to change the column name on one of the tables so that they don't collide in the UNION.