I have 3 tables with 1:N relations, something like:

create table tbl1
(
    id bigserial primary key
    name varchar unique not null
    ...
);
create table tbl2
(
    id bigserial primary key,
    tbl1_id bigint not null,
    constraint tbl2_1_fk foreign key(tbl1_id) references tbl1.id
    ...
);
create table tbl3
(
    id bigserial primary key,
    tbl2_id bigint not null,
    constraint tbl3_2_fk foreign key(tbl2_id) references tbl2.id
    ...
)

And entities for them:

@Entity
@Table(name="tbl1")
public class Ent1 implements Serializable {
...
    @OneToMany(mappedBy = "ent1", fetch = FetchType.LAZY, 
        cascade = CascadeType.ALL, orphanRemoval = true)
    private List<Ent2> ent2 = new ArrayList<>();
...
}

@Entity
@Table(name="tbl2")
public class Ent2 implements Serializable {
...
    @OneToMany(mappedBy = "ent2", fetch = FetchType.LAZY, 
        cascade = CascadeType.ALL, orphanRemoval = true)
    private List<Ent3> ent3 = new ArrayList<>();
    
    @ManyToOne(fetch = FetchType.LAZY, 
        cascade = {CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH})
    @JoinColumn(name = "tbl1_id", nullable = false)
    private Ent1 ent1;
...
}

@Entity
@Table(name="tbl3")
public class Ent3 implements Serializable {
...
    @ManyToOne(fetch = FetchType.LAZY, 
    cascade = {CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH})
    @JoinColumn(name = "tbl2_id", nullable = false)
    private Ent2 ent2;
...
}

The problem is, that I have the code that does some “import” by retrieving data from some external source and inserting it in these tables. Before importing I delete data from all three tables, then insert new, like this:

ent3Repository.deleteAll(); // Added that because of a problem
ent2Repository.deleteAll(); // Added that because of a problem
ent1Repository.deleteAll();
...
Ent1 ent1=new Ent1();
// Set ent1 fields here
ent1Repository.save();

Then, if tbl1 contains data, like a row with the name=’name1′, when I try to persist an entity, I’m getting an exception that unique constraint violated for the field “name”. Like, data weren’t deleted. But, if I do ent1Repository.count() (which I did for checking) it returns 0 and (the most weird for me) insertion is working then.

Please help – I probably don’t understand something simple. Why it is working this way? How and why calling count() helps?

Thank you!