How can I collect read-only collections in JPA / Hibernate that do not cause database updates

Question

Is it possible to create relationships in hibernate / jpa that are retrieved when the object containing the object is retrieved, but will never result in any db updates when the saved object is saved? I will try to make the requirement clear with an example.

I have a simple object B

@Entity
public class B {

    private int bId;

    @Id
    public int getBId() {
        return bId;
    }

    public void setBId(int aId) {
        bId = aId;
    }
}

And another object A, which contains a one-to-many-to-many conversion to this class.

@Entity
public class A {

    private int aId;
    private List<B> bs;

    @Id
    public int getAId() {
        return aId;
    }

    public void setAId(int aId) {
        this.aId = aId;
    }

    @ManyToMany
    @JoinTable(name = "A_B",
            joinColumns = {@JoinColumn(name = "AID")},
            inverseJoinColumns = {@JoinColumn(name = "BID")}
            )    
    public List<B> getBs() {
        return bs;
    }

    public void setBs(List<B> aBs) {
        bs = aBs;
    }
 }

When object A is extracted from db and then merged as follows

    A a = em.find(A.class, 1);
    a.getBs().size();
    em.merge(a);

merge results in the following SQL statements

Hibernate: 
    delete 
    from
        A_B 
    where
        AID=?
Hibernate: 
    insert 
    into
        A_B
        (AID, BID) 
    values
        (?, ?)
Hibernate: 
    insert 
    into
        A_B
        (AID, BID) 
    values
        (?, ?)

+ . , . , .

, : " " db?

Update:

, :

CREATE TABLE A (
        AID INTEGER NOT NULL
    )
    DATA CAPTURE NONE ;

CREATE TABLE B (
        BID INTEGER NOT NULL
    )
    DATA CAPTURE NONE ;

CREATE TABLE A_B (
        AID INTEGER NOT NULL,
        BID INTEGER NOT NULL
    )
    DATA CAPTURE NONE ;

INSERT INTO A (AID) VALUES (1);

INSERT INTO B (BID) VALUES (1);
INSERT INTO B (BID) VALUES (2);

INSERT INTO A_B (AID, BID) VALUES (1, 1);
INSERT INTO A_B (AID, BID) VALUES (1, 2);

, :

a.getBs().size();

. .

Answer 1

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@Entity
public class A {

    private int aId;
    private List<B> bs;

    @Id
    public int getAId() { return aId; }

    public void setAId(int aId) { this.aId = aId; }

    @ManyToMany
    @JoinTable(name = "A_B",
            joinColumns = {@JoinColumn(name = "AID")},
            inverseJoinColumns = {@JoinColumn(name = "BID")}
            )
    @org.hibernate.annotations.IndexColumn(name = "BS_ORDER")
    public List<B> getBs() { return bs; }

    public void setBs(List<B> aBs) { bs = aBs; }
}

Hibernate BS_ORDER / Bs.

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