Hibernate: есть звязь @ManyToMany - имею на базе UPDATE, DELETE и INSERT вместо UPDATE. Как избавится от ненужных DELETE и INSERT. Вот пример кода:
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@Entity
@Table(name = "TABLE_A")
@SequenceGenerator(name = "A_SEQ", allocationSize = 1 , initialValue = 1 , sequenceName = "A_SEQ")
public class A {
private Long number;
private java.util.Date abolishedDate;
private List<B> principalProducts;
@Id
@GeneratedValue(strategy=GenerationType.SEQUENCE, generator="A_SEQ")
@Column(name = "recid")
public Long getNumber() {
return number;
}
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@ManyToMany(fetch=FetchType.LAZY, cascade={CascadeType.REFRESH,CascadeType.MERGE})
@JoinTable(name="A_TO_B")
public List<B> getPrincipalProducts() {
return principalProducts;
}
}
и
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@Entity
@Table(name = "TABLE_B")
@SequenceGenerator(name = "B_SEQ", allocationSize = 1 , initialValue = 1 , sequenceName = "B_SEQ")
public class B implements Serializable {
@Id
@GeneratedValue(strategy=GenerationType.SEQUENCE, generator="B_SEQ")
private Integer id;
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@Column
private String name
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.
}
И когда отрабатывает след функция :
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@Transactional(propagation = Propagation.REQUIRES_NEW)
public void abolish() {
Query query = getEntityManager().createQuery("SELECTa FROM A a");
List<A> list = query.getResultList();
for (A dbo : list) {
dbo.setAbolishedDate( new java.util.Date());
List<B> plist = dbo.getPrincipalProducts();
for (B prod : plist)
System.out.println(prod.toString());
dbo = getEntityManager().merge(dbo);
}
}
в логах я вижу:
update TABLE_A set abolishedDate=?, pofType=? where id=?
delete from A_TO_B where TABLE_A_id=?
insert into A_TO_B(...) values (?, ?)
insert into A_TO_B(...) values (?, ?)
