use test; drop table if exists t; create table t (a int, b int, c timestamp, index idx(a)); set @@tidb_enable_window_function = 1; set @@session.tidb_window_concurrency = 1; explain select sum(a) over() from t; explain select sum(a) over(partition by a) from t; explain select sum(a) over(partition by a order by b) from t; explain select sum(a) over(partition by a order by b rows unbounded preceding) from t; explain select sum(a) over(partition by a order by b rows between 1 preceding and 1 following) from t; explain select sum(a) over(partition by a order by b range between 1 preceding and 1 following) from t; explain select sum(a) over(partition by a order by c range between interval '2:30' minute_second preceding and interval '2:30' minute_second following) from t; set @@session.tidb_window_concurrency = 4; explain select sum(a) over() from t; explain select sum(a) over(partition by a) from t; explain select sum(a) over(partition by a order by b) from t; explain select sum(a) over(partition by a order by b rows unbounded preceding) from t; explain select sum(a) over(partition by a order by b rows between 1 preceding and 1 following) from t; explain select sum(a) over(partition by a order by b range between 1 preceding and 1 following) from t; explain select sum(a) over(partition by a order by c range between interval '2:30' minute_second preceding and interval '2:30' minute_second following) from t; drop table if exists t1; create table t1(a int primary key, b int); insert into t1 values(1, 1), (2, 1); analyze table t1; explain select sum(a) over(partition by b) from t1; insert into t1 values(3, 3); analyze table t1; explain select sum(a) over(partition by b) from t1;