> Important: To avoid blocking concurrent transactions that obtain numbers from the same sequence, a nextval operation is never rolled back; that is, once a value has been fetched it is considered used, even if the transaction that did the nextval later aborts. This means that aborted transactions might leave unused "holes" in the sequence of assigned values.
> We don't worry too much about code quality as I believe that that is fixed at the recruitment level. Good people write good code and, more importantly, ship good products.
Good people make mistakes too. Having good tools to ensure code quality doesn't make it impossible to ship bad products, but it's definitely important.
> Important: To avoid blocking concurrent transactions that obtain numbers from the same sequence, a nextval operation is never rolled back; that is, once a value has been fetched it is considered used, even if the transaction that did the nextval later aborts. This means that aborted transactions might leave unused "holes" in the sequence of assigned values.