Primary key violation exception in auto increment column

Question

Hi All,
I am facing one issue in Multi threaded environment.
I am getting Primary key violation exception in auto increment column. I have a table and the primary key is the auto increment column, and I have a trigger which is populating this column.
5 threads are running and inserting the data in the table and throwing Primary key violation exception randomly.
create table example (
id number not null,
name varchar2(30)
alter table example
add constraint PK1example primary key (id);
create sequence example_id_seq start with 1 increment by 1;
create or replace trigger example_insert
before insert on example
for each row
begin
select example_id_seq.nextval into :new.id from dual;
end;
Any idea how to handle auto increment column(trigger) in Multi threaded environment??
Thanks,

Answer 1

user13566109 wrote:
Thanks All,
Problem was in approach; removed the trigger and placed a seq.nextval in insert query. It has resolved the issue.I very much suspect that that was not the issue.
The trigger would execute for each insertion and the nextval would have been unique for each insertion (that's how sequences work in oracle), so that wouldn't have been causing duplicates.
I suspect, more likely, that you had some other code somewhere that was using another sequence or some other method of generating the keys that was also inserting into the same table, so there was a conflict in the sources of the sequences being generated.
The way you showed you had coded above, was a perfectly normal way to assign primary keys from a sequence, and is not a problem in a multi user/threaded environment.