Avoid duplicate primary keys after database intialization in spring-boot 2 - spring

Question

The default #GeneratedValue strategy used to work in a spring boot 1.5 web app, without duplicate id conflicts of any type
... using a simple entity such as this one
// in my/package/Car.java
// ...
#Entity
public class Car {
private long id;
private String company;
private String model;
#Id
#GeneratedValue
public long getId() {
return id;
}
// ... more getters and setters
}
... and initializing the DB at start-up with
# in src/main/resources/import.sql
insert into car values (1, 'Tesla', 'Roadster');
... and later inserting another car with
Car c = new Car();
c.setCompany("Ford");
c.setModel("Pinto");
entityManager.persist(c);
entityManager.flush();
// expect no issue inserting, and a valid ID
log.info("Assigned ID is " + c.getId());
... used to result in a new Car with id 2. I do not really care about the generated ID, as long as there is no conflict. However, this same code now throws the following exception:
org.hsqldb.HsqlException: integrity constraint violation: unique constraint or index violation; SYS_PK_10095 table: CAR
(the DB is HSQL, and I would much rather not have to replace it)
... because the default sequence generation in hibernate 5.2 now does not take existing inserts into account.
What are my possible work-arounds to still allow the database to be initialized via import.sql? I know I can
use very large ids at initialization time (but this is just kicking the can down the road, and not a real solution: eventually the sequence will catch up and break things)
write my own sequence generator (but there has to be a much easier way of initializing a DB!)
use the old sequence generation (but again, why did they change it if there was no advantage to doing so? hibernate developers surely had some better way of initializing things in mind!).
somehow specify a starting value for new IDs (how do I do this in a fail-safe way? is there a property that can go into my application.properties to keep this centralized?)
I want to use this in the context of a spring-boot web app, and to keep it as simple and close to best practices as possible. Suggestions?

Answer 1

From version 5 SEQUENCE is used instead of IDENTITY for id generation. Migration from Hibernate 4 to 5
What happened?
You inserted record with ID 1 using script. Sequence remains at 1. It wants to insert 1 what is causing unique PK violation.
Solution
Don't use generation type auto. Use IDENTITY. Then inserting records by script, IDENTITY will be automatically increased. Also you don't need to insert ID value:
DECLARE temp_id INTEGER;
INSERT INTO CUSTOMERS VALUES (DEFAULT, firstname, lastname, CURRENT_TIMESTAMP);
SET temp_id = IDENTITY();
INSERT INTO ADDRESSES VALUES (DEFAULT, temp_id, address);