DROP TABLE IF EXISTS test.dst_00753; DROP TABLE IF EXISTS test.buffer_00753; SET send_logs_level = 'error'; CREATE TABLE test.dst_00753 (x UInt64, y UInt64) ENGINE = MergeTree ORDER BY tuple(); CREATE TABLE test.buffer_00753 (x UInt64, y UInt64) ENGINE = Buffer(test, dst_00753, 1, 99999, 99999, 1, 1, 99999, 99999); INSERT INTO test.buffer_00753 VALUES (1, 100); INSERT INTO test.buffer_00753 VALUES (2, 200); INSERT INTO test.buffer_00753 VALUES (3, 300); SELECT 'init'; SELECT * FROM test.dst_00753 ORDER BY x; SELECT '-'; SELECT * FROM test.buffer_00753 ORDER BY x; ALTER TABLE test.dst_00753 DROP COLUMN x, MODIFY COLUMN y String, ADD COLUMN z String DEFAULT 'DEFZ'; INSERT INTO test.buffer_00753 VALUES (4, 400); SELECT 'alt'; SELECT * FROM test.dst_00753 ORDER BY y; SELECT '-'; SELECT * FROM test.buffer_00753 ORDER BY y; OPTIMIZE TABLE test.buffer_00753; SELECT 'opt'; SELECT * FROM test.dst_00753 ORDER BY y; SELECT '-'; SELECT * FROM test.buffer_00753 ORDER BY y; SET send_logs_level = 'warning'; DROP TABLE IF EXISTS test.dst_00753; DROP TABLE IF EXISTS test.buffer_00753;