CREATE TABLE material
(
  mid bigserial NOT NULL,
...
  active_from timestamp without time zone,
....
  CONSTRAINT material_pkey PRIMARY KEY (mid),
)
 
CREATE INDEX i_test_t_year
  ON material
  USING btree
  (date_part('year'::text, active_from));

SELECT mid FROM material ORDER BY mid DESC
"Index Only Scan Backward using material_pkey on material  (cost=0.29..3573.20 rows=100927 width=8)"

SELECT * FROM material ORDER BY active_from DESC
"Sort  (cost=12067.29..12319.61 rows=100927 width=16)"
"  Sort Key: active_from"
"  ->  Seq Scan on material  (cost=0.00..1953.27 rows=100927 width=16)"