DROP TABLE IF EXISTS min_max_with_nullable_string; CREATE TABLE min_max_with_nullable_string ( t DateTime, nullable_str Nullable(String), INDEX nullable_str_min_max nullable_str TYPE minmax GRANULARITY 8192 ) ENGINE = MergeTree ORDER BY (t); INSERT INTO min_max_with_nullable_string(t) VALUES (now()) (now()); SELECT count() FROM min_max_with_nullable_string WHERE nullable_str = '.'; INSERT INTO min_max_with_nullable_string(t, nullable_str) VALUES (now(), '.') (now(), '.'); SELECT count() FROM min_max_with_nullable_string WHERE nullable_str = '.'; INSERT INTO min_max_with_nullable_string(t, nullable_str) VALUES (now(), NULL) (now(), '.') (now(), NULL) (now(), '.') (now(), NULL); SELECT count() FROM min_max_with_nullable_string WHERE nullable_str = '.'; SELECT count() FROM min_max_with_nullable_string WHERE nullable_str = ''; DROP TABLE min_max_with_nullable_string;