DROP TABLE IF EXISTS test.replaceall; CREATE TABLE test.replaceall (str FixedString(3)) ENGINE = Memory; INSERT INTO test.replaceall VALUES ('foo'); INSERT INTO test.replaceall VALUES ('boa'); INSERT INTO test.replaceall VALUES ('bar'); INSERT INTO test.replaceall VALUES ('bao'); SELECT str, replaceAll(str, 'o', '*') AS replaced FROM test.replaceall ORDER BY str ASC; DROP TABLE test.replaceall; CREATE TABLE test.replaceall (date Date DEFAULT today(), fs FixedString(16)) ENGINE = MergeTree(date, (date, fs), 8192); INSERT INTO test.replaceall (fs) VALUES ('54db0d43009d\0\0\0\0'), ('fe2b58224766cf10'), ('54db0d43009d\0\0\0\0'), ('fe2b58224766cf10'); SELECT fs, replaceAll(fs, '\0', '*') FROM test.replaceall ORDER BY fs ASC; DROP TABLE test.replaceall;