Hibernate @generatedvalue for HSQLDB

Question

I have the following definition for an id field in an entity that is mapped to a table in HSQLDB.

...
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
@Colu         


        

Answer 1

I had the same issue when using a JpaSchemaGenerator utility class that I wrote.

When generating the schema for a org.hibernate.dialect.HSQLDialect (where I use a SEQUENCE to generate my unique IDs), I use the following Hibernate property:

hibernate.id.new_generator_mappings=true

This results in the following CREATE statement:

CREATE TABLE BATCH (
    BAT_ID NUMBER(19,0) NOT NULL,
    BAT_EXPIRY_DATE TIMESTAMP,
    BAT_NUMBER VARCHAR2(255 CHAR),
    BAT_MAT_ID NUMBER(19,0),
    PRIMARY KEY (BAT_ID)
);

But when I use this same property in my utility class to generate a schema using the org.hibernate.dialect.HSQLDialect, I get the following CREATE statement:

CREATE TABLE BATCH (
    BAT_ID BIGINT NOT NULL,
    BAT_EXPIRY_DATE TIMESTAMP,
    BAT_NUMBER VARCHAR(255),
    BAT_MAT_ID BIGINT,
    PRIMARY KEY (BAT_ID)
);

This would mean that if I created a Batch without an ID, it would not generate it for me and the NOT NULL constraint would cause an exception.

If I change the Hibernate property to the following:

hibernate.id.new_generator_mappings=false

Then it would generate the following CREATE statement:

CREATE TABLE BATCH (
    BAT_ID BIGINT GENERATED BY DEFAULT AS IDENTITY (START WITH 1),
    BAT_EXPIRY_DATE TIMESTAMP,
    BAT_NUMBER VARCHAR(255),
    BAT_MAT_ID BIGINT,
    PRIMARY KEY (BAT_ID)
);

Which works perfectly when creating JPA entities with Hibernate.