DROP TABLE IF EXISTS prewhere;

CREATE TABLE prewhere (light UInt8, heavy String) ENGINE = MergeTree ORDER BY tuple();
INSERT INTO prewhere SELECT 0, randomPrintableASCII(10000) FROM numbers(10000);
SELECT arrayJoin([light]) != 0 AS cond, length(heavy) FROM prewhere WHERE light != 0 AND cond != 0;

DROP TABLE prewhere;