set allow_experimental_projection_optimization = 1; drop table if exists t; create table t (i int, j int, projection x (select * order by j)) engine MergeTree partition by i order by i; insert into t values (1, 2); alter table t detach partition 1; alter table t attach partition 1; select count() from system.projection_parts where database = currentDatabase() and table = 't' and active; drop table t;