drop table if exists data; create table data (part Int) engine=MergeTree() order by tuple() partition by part; insert into data values (1)(2); -- { echoOn } select * from data prewhere indexHint(_partition_id = '1'); -- TODO: optimize_use_implicit_projections ignores indexHint (with analyzer) because source columns might be aliased. select count() from data prewhere indexHint(_partition_id = '1') settings optimize_use_implicit_projections = 0; select * from data where indexHint(_partition_id = '1'); select count() from data where indexHint(_partition_id = '1') settings optimize_use_implicit_projections = 0;