SET max_threads = 2; SET optimize_read_in_order = 1; DROP TABLE IF EXISTS TESTTABLE4; CREATE TABLE TESTTABLE4 (_id UInt64, pt String, l String ) ENGINE = MergeTree() PARTITION BY (pt) ORDER BY (_id); INSERT INTO TESTTABLE4 VALUES (0,'1','1'), (1,'0','1'); SELECT _id FROM TESTTABLE4 PREWHERE l IN (select '1') ORDER BY _id DESC LIMIT 10; SET experimental_use_processors=1; SELECT _id FROM TESTTABLE4 PREWHERE l IN (select '1') ORDER BY _id DESC LIMIT 10; DROP TABLE TESTTABLE4;