How to compare timestamp with integer in Postgres? - postgresql

Question

I want to have a trigger that would remove existing records where they have lived for more then 10 mins
drop table if exists authorization_code;
create table if not exists authorization_code(
id int generated always as identity,
created_at timestamptz not null
);
drop function if exists remove_expired();
create function remove_expired()
returns trigger
language plpgsql
as $$
begin
--NOTE 10 mins as recommended by the OAuth2 spec
delete from authorization_code where now() - created_at > 600;
return NEW;
end;
$$;
drop trigger if exists clean_up_expired_code on authorization_code;
create trigger clean_up_expired_code
before insert
on authorization_code
for each row
execute procedure remove_expired();
But right now if I insert, I would get an error like this:
sso=# insert into authorization_code(created_at) values(now());
ERROR: operator does not exist: interval > integer
LINE 1: ...lete from authorization_code where now() - created_at > 600
^
HINT: No operator matches the given name and argument types. You might need to add explicit type casts.
QUERY: delete from authorization_code where now() - created_at > 600
CONTEXT: PL/pgSQL function remove_expired() line 4 at SQL statement
What is the correct way to achieve what I want?

Answer 1

The result of subtracting two timestamps is an interval so you can directly compare that:
where now() - created_at > interval '10 minutes';
Or if you want to provide duration as e.g. a parameter indicating the number of seconds:
where now() - created_at > make_interval(secs => 600);

Answer 2

Try using this modified version of the remove_expired() function
halley=> \sf remove_expired
CREATE OR REPLACE FUNCTION public.remove_expired()
RETURNS trigger
LANGUAGE plpgsql
AS $function$
begin
--NOTE 10 mins as recommended by the OAuth2 spec
delete from authorization_code where EXTRACT(EPOCH FROM CURRENT_TIMESTAMP)-EXTRACT(EPOCH FROM created_at) > 600;
return NEW;
end;
$function$