Re: creating "job numbers"

postgresql wrote:
> Jan,
>
> Thanks, I must be missing something here. Bear with me, I am
> trying to form an intelligent question.
>
> Using the serial data type... I don't understand when the backend
> would skip a number.
> If the db is assigning the number with the insert, then if two (or
> more) clients are trying to insert into the db at the exact same time,
> only those that are successful should get a number. I am trying to
> envision a situation where two clients hit at the same time and
> because of problem with the insert, one aborts and the serial data
> number is skipped. I would have assumed that the aborted insert is
> just skipped no harm done.

Concurrency will not cause your transactions to abort. It's
just if you do

BEGIN;
INSERT INTO ...
ROLLBACK;

that the generated sequence numbers don't get rolled back. So
you might find job numbers 1, 2, 4 where 3 is missing because
it's transaction aborted (explicit rollback or error during
processing). The serial data type will never fill in those
gaps.

Jan

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