DROP TABLE IF EXISTS weird_mmx; CREATE TABLE weird_mmx (x Array(UInt64)) ENGINE = TinyLog; -- this triggers overlapping matches in LZ4 decompression routine; 915 is the minimum number -- see comment in LZ4_decompression_faster.cpp about usage of MMX registers INSERT INTO weird_mmx SELECT range(number % 10) FROM system.numbers LIMIT 915; SELECT sum(length(*)) FROM weird_mmx; DROP TABLE weird_mmx;