DROP TABLE IF EXISTS sample_00579_1; DROP TABLE IF EXISTS sample_00579_2; DROP TABLE IF EXISTS sample_merge_00579; set allow_deprecated_syntax_for_merge_tree=1; CREATE TABLE sample_00579_1 (x UInt64, d Date DEFAULT today()) ENGINE = MergeTree(d, intHash64(x), intHash64(x), 10); CREATE TABLE sample_00579_2 (x UInt64, d Date DEFAULT today()) ENGINE = MergeTree(d, intHash64(x), intHash64(x), 10); INSERT INTO sample_00579_1 (x) SELECT number AS x FROM system.numbers LIMIT 1000; INSERT INTO sample_00579_2 (x) SELECT number AS x FROM system.numbers LIMIT 2000; CREATE TABLE sample_merge_00579 AS sample_00579_1 ENGINE = Merge(currentDatabase(), '^sample_00579_\\d$'); SET max_threads = 1; SELECT _sample_factor FROM merge(currentDatabase(), '^sample_00579_\\d$'); DROP TABLE sample_00579_1; DROP TABLE sample_00579_2; DROP TABLE sample_merge_00579;