Hibernate is not auto creating sequencies to database when using auto creating of tables

Question

I want to create my database tables automatically with Hibernate and Postgresql, but I get errors about sequences. Is it possible to auto create sequences too with Hibernate, or do I have generate sequences manually?

Example of my entity:

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.SequenceGenerator;
import javax.persistence.Table;
import javax.persistence.UniqueConstraint;

@Entity
@Table(uniqueConstraints = { @UniqueConstraint( columnNames =  { "id" }) })
@SequenceGenerator(name="SEQ_EXAMPLE_ID", sequenceName="example_id_seq", allocationSize=1)
public class Example {

    @Id
    @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="SEQ_EXAMPLE_ID")
    private Long id;

    public Long getId() {
        return id;
    }
    public void setId(Long id) {
        this.id = id;
    }
    public String g
}

Hibernate config:

hbm2ddl.auto=create-drop
hibernate.dialect=org.hibernate.dialect.PostgreSQLDialect
hibernate.show_sql=true 

Exceptions:

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.hibernate.exception.SQLGrammarException: could not get next sequence value

org.postgresql.util.PSQLException: ERROR: relation "example_id_seq" does not exist

Answer 1

Your mapping seems correct and I suggest activating logging of the following category to see what is happening exactly:

• org.hibernate.tool.hbm2ddl: Log all SQL DDL statements as they are executed

Set it to DEBUG and check the DDL statements (maybe update the question with the relevant parts).

PS: An allocationSize=1 is not very wise, using the default would be better. But that's unrelated.

References

• Hibernate Core Reference Guide
  • 3.5. Logging

Answer 2

You have to enable automatic schema creation in application.properties as described in Hibernate docs:

hibernate.hbm2ddl.auto = create

or when using Spring:

spring.jpa.hibernate.ddl-auto = create

But the general recommendation is not to use this in production, see Hibernate: hbm2ddl.auto=update in production?

Use database schema migration tools like Liquibase or Flyway instead.