Hibernate Update Index or Constraint after DB has been created

Question

I am trying to add a unique constraint on a column but it works if I recreate database but doesn't work when I update already existing database.

Similar with adding unique to index. Is there a reason why hibernate doesn't update column if database already exists? I am using Dropwizard.

@Entity
@Table(name = EnrollmentStatusEntity.TABLE_NAME,
        indexes = {
            @Index(name = Student_RollNo,
                    columnList = rollNo,
                    unique = true)
        })
@Data
public class Student {
    public static final String TABLE_NAME = "Student";

    @Id
    @NonNull
    @Column(name = ID, unique = true, updatable = false, nullable = false)
    private String id;

    @NonNull
    @Column(name = COMPARTMENT_ID, unique=true, nullable = false, updatable = false)
    private String rollNo;

You would need to use `spring.jpa.hibernate.ddl-auto=update` (or similar property, that's what Spring Boot uses) to have Hibernate update the database schema. — Kayaman, Nov 17 '20 at 19:14
Does this work for any schema changes in entities ? Does this work with dropwizard as well ? — D86658, Nov 17 '20 at 19:36
ddl-auto=update would drop and create a new schema does this mean all the data will be lost on recreation ? https://docs.jboss.org/hibernate/orm/4.3/manual/en-US/html_single/ — D86658, Nov 17 '20 at 19:52
Yeah could be. The annotations for constraints or indexes aren't very useful since you'll never know if they represent the true state of the database, and they're a poor tool for schema definition anyway. — Kayaman, Nov 17 '20 at 20:26

score 0 · Answer 1 · answered Nov 17 '20 at 23:31

Try to add this on your existing Hibernate class settings.put(Environment.HBM2DDL_AUTO, "update");

it should work with this code but be careful when adding a table to the db if the table isnt NULL then it wont update the db (must be 0 on creating 1st time then change value inside the code or through the browser)

score 0 · Answer 2 · answered Dec 07 '20 at 23:38

You can control the hibernate's automatic schema generation through your dropwizard project's configuration yaml file:

database:
  properties:
    hibernate.hbm2ddl.auto: update

This will update the schema automatically every time you run the application, if your db properties are otherwise correctly set in the configuration file.

This is usually not a good idea for production use.

Dropwizard Migrations uses Liquibase to track, version and deploy database changes. I would recommend using Dropwizard Migration and setting hibernate.hbm2ddl.auto: validate, that way you manage the database schema changes with Liquibase and validate with hibernate that the database schema matches the java entities.

Hibernate Update Index or Constraint after DB has been created

2 Answers2