DROP TABLE IF EXISTS numbers1; DROP TABLE IF EXISTS numbers2; CREATE TABLE numbers1 ENGINE = Memory AS SELECT number FROM numbers(1000); CREATE TABLE numbers2 ENGINE = Memory AS SELECT number FROM numbers(1000); SELECT * FROM merge(currentDatabase(), '^numbers\\d+$') SAMPLE 0.1; -- { serverError 141 } DROP TABLE numbers1; DROP TABLE numbers2; CREATE TABLE numbers1 ENGINE = MergeTree ORDER BY intHash32(number) SAMPLE BY intHash32(number) AS SELECT number FROM numbers(1000); CREATE TABLE numbers2 ENGINE = MergeTree ORDER BY intHash32(number) SAMPLE BY intHash32(number) AS SELECT number FROM numbers(1000); SELECT * FROM merge(currentDatabase(), '^numbers\\d+$') SAMPLE 0.01; DROP TABLE numbers1; DROP TABLE numbers2;