Hibernate: GenerationType.IDENTITY disables JDBC batching

Hibernate must execute each insert to learn the generated id, so it cannot batch them.

Code

@Id @GeneratedValue(strategy = GenerationType.IDENTITY)   // no batching
Long id;

@Id @GeneratedValue(strategy = GenerationType.SEQUENCE,
                    generator = "order_seq")
@SequenceGenerator(name = "order_seq", allocationSize = 50)  // batches fine
Long id;

Output

IDENTITY: 1000 inserts = 1000 round trips.
SEQUENCE with allocationSize 50: 20 sequence calls + batched inserts.

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Published 2026-08-11