/*Создане таблицы для примера*/
CREATE TABLE test.test_material
(  id integer,
    mat text,
    comp text,
  ver integer);
INSERT INTO test.test_material(id, mat, comp, ver) VALUES ( 1,'Mat_1','Comp_1', 0);
INSERT INTO test.test_material(id, mat, comp, ver) VALUES ( 2,'Mat_1','Comp_X', 0);
INSERT INTO test.test_material(id, mat, comp, ver) VALUES ( 3,'Mat_1','Comp_2', 1);
INSERT INTO test.test_material(id, mat, comp, ver) VALUES ( 4,'Mat_1','Comp_X', 1);
INSERT INTO test.test_material(id, mat, comp, ver) VALUES ( 5,'Mat_1','Comp_3', 2);
INSERT INTO test.test_material(id, mat, comp, ver) VALUES ( 6,'Mat_1','Comp_X', 2);
INSERT INTO test.test_material(id, mat, comp, ver) VALUES ( 7,'Mat_2','Comp_Y', 0);
INSERT INTO test.test_material(id, mat, comp, ver) VALUES ( 8,'Mat_2','Comp_W', 0);

/*Сам скрипт*/
select mat, 
       comp
from (SELECT id,  mat,  comp, ver,  max(ver) over(partition by mat) as max_ver
         FROM test.test_material
       ) as t
where t.ver = t.max_ver;