is there a way to avoid calling nextval() if the insert fails in PostgreSQL?

Question

In a PostgreSQL database I have a table with a primary key and another field which needs to be unique.

  CREATE TABLE users (
    id      INTEGER PRIMARY KEY         


        

Answer 1

If you need gapless sequences - there are ways to do it, but it's not trivial, and definitely much slower.

Also - if you worry about "using too many ids" - just define id as bigserial.