Remove an element from @ElementCollection. Efficiency of List vs Set

Hibernate ORM
1

I have an entity with two @ElementCollection columns:

@Entity
public class User1 {
    @Id
    @GeneratedValue
    private int id;

    @ElementCollection
    private Set<String> stringsSet = new HashSet<>();

    @ElementCollection
    private List<String> stringsList = new ArrayList<>();
    
    ...
}

When I remove one element from the stringsSet, hibernate generates one “delete” command:

    delete 
    from
        User1_stringsSet 
    where
        User1_id=? 
        and stringsSet=?

When I remove one element from the stringsList, hibernate generates “delete” that removes all rows and “insert” for each remaining element in the collection:

    delete 
    from
        User1_stringsList 
    where
        User1_id=?

    insert 
    into
        User1_stringsList
        (User1_id, stringsList) 
    values
        (?, ?)

    insert 
    into
        User1_stringsList
        (User1_id, stringsList) 
    values
        (?, ?)

   ... etc (same insert for each remain value in stringsList)

From these two examples we can see that the generated code for the stringsSet is much more efficient.
Question: why does hibernate generate different and inefficient code for the stringsList?

2

Your list can contain duplicates, so Hibernate ORM cannot use the same “efficient” code when your property is a list: it would delete all occurrences of the string instead of just one.