@GeneratedValue strategies in JPA.

1. IDENTITY

• Relies on the database ID column (Auto-increment).
• Caveat: Disables batch inserts because Hibernate needs to perform the insert to get the ID.

2. SEQUENCE

• Uses a database sequence object.
• Preferred: Supports batch inserts as IDs can be pre-fetched in batches (allocationSize).

3. TABLE

• Uses a separate table to simulate a sequence.
• Slowest: High overhead due to table locks and synchronization. Only used if the DB doesn't support sequences or identity.

4. AUTO

• Hibernate chooses the strategy based on the DB dialect (often defaults to SEQUENCE or TABLE).