DROP TABLE IF EXISTS t_sample_factor;

CREATE TABLE t_sample_factor(a UInt64, b UInt64) ENGINE = MergeTree ORDER BY (a, b) SAMPLE BY b;
INSERT INTO t_sample_factor(a, b) VALUES (1, 2), (3, 4);

SELECT uniq(b) * any(_sample_factor) FROM t_sample_factor SAMPLE 200000;

SELECT uniq(b) * any(_sample_factor) FROM t_sample_factor SAMPLE 200000 WHERE a < -1;
SELECT uniq(b) * any(_sample_factor) FROM t_sample_factor SAMPLE 200000 PREWHERE a < -1;

DROP TABLE t_sample_factor;