Can be GenerationType.SEQUENCE optimized to not to perform query to sequence on every ID update?-CodePudding

When I use

@Id
@GeneratedValue(
    strategy = GenerationType.SEQUENCE
)
private Long id;

Does it mean, on every entity creation ORM framework makes a query to DB to update sequence table? Can it be optimized, e.g. by chunks?

CodePudding user response：

@GeneratedValue further exposes an option to define a generator :

@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "id_generator")
@SequenceGenerator(name="id_generator", sequenceName = "id_seq", allocationSize=50)
private Long id;

Enabling this , Hibernate will allocate a batch of 50 ids per session.This batch will be then prefetch for a range of 50 which can provide better performance.

There are still some additional things to be considered , such as , if a session is closed/killed prematurely we will lose the allocated sequence ids.

The following deep-dive talks more about the caveats/soltions : https://www.jpa-buddy.com/blog/the-ultimate-guide-on-db-generated/