[hibernate-issues] [JIRA] (HHH-15476) Batch save for Postgresql sequence does't work very well.

yo ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=63123de... ) *updated* an issue Hibernate ORM ( https://hibernate.atlassian.net/browse/HHH?atlOrigin=eyJpIjoiMTJhZTc5MWM2... ) / Improvement ( https://hibernate.atlassian.net/browse/HHH-15476?atlOrigin=eyJpIjoiMTJhZT... ) HHH-15476 ( https://hibernate.atlassian.net/browse/HHH-15476?atlOrigin=eyJpIjoiMTJhZT... ) Batch save for Postgresql sequence does't work very well. ( https://hibernate.atlassian.net/browse/HHH-15476?atlOrigin=eyJpIjoiMTJhZT... ) Change By: yo ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=63123de... ) *I want to Batch save data to Postgresql* see demo in  [*github* |https://github.com/coding2world/sb-jpa-batch-insert-demo] first, I write java code like this. below is pojo’s definition. {code:java}@Data @Entity @Table(name = "city") @AllArgsConstructor public class City { @Id @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "city_id_gen") @SequenceGenerator(name = "city_id_gen", sequenceName = "public.city_id_seq", allocationSize = 5) private Long id; private String name; private int population; public City(String name, int population) { this.name = name; this.population = population; } public City() { } }{code} Repository class. {code:java}public interface CityRepo extends JpaRepository<City, Long> {}{code} invoke the Repository class. {code:java}cityRepo.saveAll(range(1, 10) .mapToObj(i -> new City("beautiful", (int)System.currentTimeMillis()/1000)) .collect(toList()));{code} second is my sql. {code:sql}CREATE TABLE city(id serial PRIMARY KEY, name VARCHAR(255), population integer);{code} *My question below:* When  I call {{SELECT nextval('city_id_seq')}} return 100. *It means 99 and 98  have  been  used.* Suppose  the value of the parameter  named  {{allocationSize}} of the annotation named {{SequenceGenerator}}  is 3 , So hibernate should generate 3 id once call {{SELECT nextval('city_id_seq')}}. According to the below code {code:java}org.hibernate.id.enhanced.PooledOptimizer#generate{code} {{SELECT nextval('city_id_seq')}} return 100 , the 3 sequence is 98, 99, 100. But  *99 and 98  have  been  used.* I think *Hibernate should call* {{SELECT setval ('city_id_seq', nextval ('city_id_seq')+3)}} is returns 102. the 3 sequence is 100, 101, 102. ( https://hibernate.atlassian.net/browse/HHH-15476#add-comment?atlOrigin=ey... ) Add Comment ( https://hibernate.atlassian.net/browse/HHH-15476#add-comment?atlOrigin=ey... ) Get Jira notifications on your phone! Download the Jira Cloud app for Android ( https://play.google.com/store/apps/details?id=com.atlassian.android.jira.... ) or iOS ( https://itunes.apple.com/app/apple-store/id1006972087?pt=696495&ct=Em... ) This message was sent by Atlassian Jira (v1001.0.0-SNAPSHOT#100206- sha1:3ac329d )