postgres scd2 (slow changing dimension) trigger implementation

postgres_scd2.sql

create table records (
	record_id int,
	record_name varchar(100),
	record_value int,
	date_start timestamp default now(),
	date_end timestamp default null,
	primary key(record_id, record_name, date_start)	
);

insert into records (record_id, record_name, record_value)
values 
	(1, 'r1', 30),
	(2, 'r2', 42)
;

select * from records;

CREATE OR REPLACE function public.scd2()
returns trigger 
AS $BODY$
	BEGIN
		update records 
		set date_end = now()
		where record_name=new.record_name
		and date_end is null;
		return new;
	END;
$BODY$
LANGUAGE plpgsql;


CREATE TRIGGER example_trigger before INSERT ON records
FOR EACH ROW EXECUTE PROCEDURE scd2();

insert into records (record_id, record_name, record_value)
values 
	(1, 'r1', 45)
;

select * from records;