DROP TABLE IF EXISTS t_materialize_delete; CREATE TABLE t_materialize_delete (id UInt64, v UInt64) ENGINE = MergeTree ORDER BY id PARTITION BY id % 10; SET mutations_sync = 2; INSERT INTO t_materialize_delete SELECT number, number FROM numbers(100); SELECT 'Inserted'; SELECT count(), sum(v) FROM t_materialize_delete; SELECT count(), sum(rows), sum(has_lightweight_delete) FROM system.parts WHERE database = currentDatabase() AND table = 't_materialize_delete' AND active; SELECT 'Lighweight deleted'; DELETE FROM t_materialize_delete WHERE id % 7 = 3; SELECT count(), sum(v) FROM t_materialize_delete; SELECT count(), sum(rows), sum(has_lightweight_delete) FROM system.parts WHERE database = currentDatabase() AND table = 't_materialize_delete' AND active; SELECT 'Mask applied'; ALTER TABLE t_materialize_delete APPLY DELETED MASK; SELECT count(), sum(v) FROM t_materialize_delete; SELECT count(), sum(rows), sum(has_lightweight_delete) FROM system.parts WHERE database = currentDatabase() AND table = 't_materialize_delete' AND active; SELECT 'Lighweight deleted'; DELETE FROM t_materialize_delete WHERE id % 7 = 4; SELECT count(), sum(v) FROM t_materialize_delete; SELECT count(), sum(rows), sum(has_lightweight_delete) FROM system.parts WHERE database = currentDatabase() AND table = 't_materialize_delete' AND active; SELECT 'Mask applied in partition'; ALTER TABLE t_materialize_delete APPLY DELETED MASK IN PARTITION 5; SELECT count(), sum(v) FROM t_materialize_delete; SELECT count(), sum(rows), sum(has_lightweight_delete) FROM system.parts WHERE database = currentDatabase() AND table = 't_materialize_delete' AND active; DROP TABLE t_materialize_delete;