BUG #14909: nextval() bug

The following bug has been logged on the website:

Bug reference:      14909
Logged by:          Max Rys
Email address:      personal@rysmax.com
PostgreSQL version: 10.1
Operating system:   macOS 10.12.6
Description:

I run this simple queries on PostgeSQL 9.6 and 10.1:

DROP TABLE IF EXISTS "user";
CREATE TABLE "user" (
  id serial primary key not null,
  email varchar(64) not null
);
INSERT INTO "user" (id, email) VALUES ('1', 'admin@example.com');
INSERT INTO "user" (id, email) VALUES ('2', 'user@example.com');

All done without errors.



When i try to run the query bellow:

INSERT INTO "user" (email) VALUES ('test@example.com');

and got the next error in pgAdmin and from the PHP:

ERROR:  duplicate key value violates unique constraint "user_pkey"
DETAIL:  Key (id)=(1) already exists.

but when i try to run this query 2 times the query executed without errors
on 3rd time.



I think this is a bug in nextval() function.