In my life as a professional PostgreSQL consultant (https://www.cybertec-postgresql.com), I have seen a couple of mistakes that are made again and again. If there are constants in life, these typical mistakes are definitely some of the things that never change.
Here is my favorite:
|
Transaction 1 |
Transaction 2 |
|
BEGIN; |
BEGIN; |
|
SELECT max(id) FROM product; |
SELECT max(id) FROM product; |
|
User will see 17 |
User will see 17 |
|
User will decide to use 18 |
User will decide to use 18 |
|
INSERT INTO product ... VALUES (18, ...) |
INSERT INTO product ... VALUES (18, ...) |
|
COMMIT; |
COMMIT; |
In this case, there will be either a duplicate key violation or two identical entries. ...
