Gaps between primary key id in sql table

Question

I have a table which is:

CREATE SEQUENCE id_seq;
CREATE TABLE public.\"UserInfo\"
(
  id bigint NOT NULL DEFAULT nextval(\'id_seq\'),
  phone text,
  passwor         


        

Answer 1

This is the way sequences work.

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 and will not be returned again. This is true even if the surrounding transaction later aborts, or if the calling query ends up not using the value.

As pointed out in the comments there's no harm in having gaps in sequences. If you delete some rows in your table for what ever reason you are creating gaps in your primary key values and you wouldn't normally bother with resetting them to make them sequential.

If you insist on creating a gapless sequence, read this article: http://www.varlena.com/GeneralBits/130.php and be prepared for slow inserts.