Optimizing a query in PostgreSQL - sql

Question

CREATE TABLE master.estado_movimiento_inventario
(
id integer NOT NULL,
eliminado boolean NOT NULL DEFAULT false,
fundamentacion text NOT NULL,
fecha timestamp without time zone NOT NULL,
id_empresa integer NOT NULL,
id_usuario integer NOT NULL,
id_estado integer NOT NULL,
id_movimiento integer NOT NULL,
se_debio_tramitar_hace bigint DEFAULT 0,
CONSTRAINT "PK15estadomovtec" PRIMARY KEY (id)
)
WITH (
OIDS=FALSE
);
ALTER TABLE master.estado_movimiento_inventario
OWNER TO postgres;
This table tracks the state of every inventory movement in my business logic. So, every movement that is not ended yet (there is not any id_estado =3 or id_estado=4 for any id_movimiento in the master.estado_movimiento_inventario table) must store in its last state's se_debio_tramitar_hace field the difference between now() and fecha field every time a scheduled task runs (Windows).
The query I built in order to do so is this:
with update_time as(
SELECT distinct on(id_movimiento) id
from master.estado_movimiento_inventario
where id_movimiento not in (
select id_movimiento
from master.estado_movimiento_inventario
where id_estado = 2 or id_estado=3
) order by id_movimiento, id desc
)
update master.estado_movimiento_inventario mi
set se_debio_tramitar_hace= EXTRACT(epoch FROM now()::timestamp - mi.fecha )/3600
where mi.id in (select id from update_time);
This works as expected but I suspect it is not optimal, specially in the update operation and here is my biggest doubt: what is optimal when performing this update operation:
Perform the updates as it currently does
or
The equivalent of postgresql function to this:
foreach(update_time.id as row_id){
update master.estado_movimiento_inventario mi set diferencia = now() - mi.fecha where mi.id=row_id;
}
Sorry if I am not explicit enough, I have not much experience working with databases, although I have understood the theory behind, yet not worked too much with it.
Edit
Please notice the id_estado is not unique per id_movimiento, just like the picture shows:

Answer 1

I think this improves the CTE:
with update_time as (
select id_movimiento, max(id) as max_id
from master.estado_movimiento_inventario
group by id_movimiento
having sum( (id_estado in (2, 3))::int ) = 0
)
update master.estado_movimiento_inventario mi
set diferencia = now() - mi.fecha
where mi.id in (select id from update_time);
If the last id would be the one in the "2" or "3" state, I would simply do:
update master.estado_movimiento_inventario mi
set diferencia = now() - mi.fecha
where mi.id = (select max(mi2.id)
from master.estado_movimiento_inventario mi
where mi2.id_movimiento = mi.id_movimiento
) and
mi.id_estado not in (2, 3);