Да, документацията не изглежда точна.
Като заобиколно решение можете да опитате да приложите вложени материализирани изгледи.
CREATE MATERIALIZED VIEW mv1
REFRESH FAST ON COMMIT
AS
SELECT col1,
COUNT(col1) count_col1
FROM test_table
GROUP BY col1
ALTER MATERIALIZED VIEW mv1 ADD CONSTRAINT pk_mv1 PRIMARY KEY (col1)
CREATE MATERIALIZED VIEW LOG ON mv1 WITH PRIMARY KEY;
CREATE MATERIALIZED VIEW MV2
REFRESH FAST ON COMMIT AS
SELECT col1,
count_col1
FROM mv1
WHERE count_col1 > 1