带有 Postgres 的 Spring JPA - 从一开始就重置 ID 生成

Question

I was using following code to persist an entity to Postgres:

@Entity
public class TwEvent {

    @Id
    @GeneratedValue
    private Long id;

    private String type;
}



@Repository
public class TwEventDAO {

   @Autowired
   private TwEventRepo repo;

   public void save(TwEvent twEvent) {
     repo.save(twEvent);
   }
}


public interface TwEventRepo extends JpaRepository<TwEvent,Long>{

}

It was working for ~30.000 records, but when I launched my app today, I get SQL error:

2019-01-13 19:57:48:432 WARN  http-nio-8081-exec-4 o.h.e.j.s.SqlExceptionHelper:127 - SQL Error: 0, SQLState: 23505
2019-01-13 19:57:48:432 ERROR http-nio-8081-exec-4 o.h.e.j.s.SqlExceptionHelper:129 - ERROR: duplicate key value violates unique constraint "tw_event_pkey"
  Detail: Key (id)=(34) already exists.
2019-01-13 19:57:48:434 INFO  http-nio-8081-exec-4 o.h.e.j.b.i.AbstractBatchImpl:193 - HHH000010: On release of batch it still contained JDBC statements

Looks like Postgres started generating Ids from start and ignores already existing records. Restarting didn't help, neither using EntityManager. App works fine with new clean DB. Any ideas how to fix a DB so it would generate right id?

SOLVED:

CREATE TABLE tw_event2 AS TABLE tw_event;

then I removed the original table and renamed a copy to tw_event. After that next ID was last+1 as expected. There was no need to change the code. No idea what caused this error though

Answer 1

如果您当然不使用序列，则最好指定类似@GeneratedValue(strategy = GenerationType.IDENTITY)否则您将放置@GeneratedValue(strategy = GenerationType.SEQUENCE) ，以确保用于生成 id 的策略是总是一样。