Reattempt of insert after a ORA-0001 unique constraint violation

Question

Hi,
I'm inserting into a table. The primary key on this table is made up of the user id and a one-up transaction number. Unfortunately, I cannot change the design of this table.
Because I have to query the table to get the next transaction number before I insert into the table, I sometimes get a ORA-0001 (unique constraint violation) error because some other session grabbed the next transaction number and committed before I did.
To deal with this I retry the insert, that is, read the table again for the next tran number and insert. I allow for this up to 3 times. If after the third attempt I fail again, I rollback.
I'm seeing 3 records in the table.
So here are my questions: Do I need to rollback when I get the ORA-0001 error? I thought I wouldn't have to. If I do, why? The insert failed, how could the commit statement commit 3 records?
Thanks!

Answer 1

No, the userid and transaction numbers are not the same (combined) for each of the 3 rows.
Here is the logic to retry again when I get a ORA-0001:
PROCEDURE insert_record(
table1_rec_in IN table1%ROWTYPE,
tran_number OUT table1.trans_number%TYPE,
attempt_number IN PLS_INTEGER)
IS
next_tran_number table1.trans_number%TYPE;
BEGIN
SELECT NVL(MAX(trans_number), 0) + 1
INTO next_tran_number
FROM table1
WHERE userid = table1_rec_in.table1_userid;
INSERT INTO table1
(userid,
trans_number,
amount,
transdate)
VALUES
(table1_rec_in.userid,
next_tran_number,
table1_rec_in.amount,
SYSDATE);
tran_number := next_tran_number;
EXCEPTION
WHEN DUP_VAL_ON_INDEX THEN
IF attempt_number < 3
THEN
DECLARE
next_attempt_number PLS_INTEGER;
BEGIN
next_attempt_number := attempt_number + 1;
insert_record(
table1_rec_in,
tran_number,
next_attempt_number);
END;
ELSE
RAISE unable_to_insert_rec;
END IF;
WHEN OTHERS THEN
RAISE unable_to_insert_rec;
END;
I'm using recursion to try the insert again. Is this the source of my problems? I don't see it and can't reproduce it.