github.com/matrixorigin/matrixone@v1.2.0/test/distributed/cases/optimizer/union.test (about)

     1  drop database if exists d1;
     2  create database d1;
     3  use d1;
     4  drop table if exists t1;
     5  drop table if exists t2;
     6  create table t1(c1 int primary key, c2 int, c3 int);
     7  create table t2(c1 int, c2 int, c3 int, primary key(c1,c2));
     8  -- @separator:table
     9  explain select * from t1 union select * from t2;
    10  -- @separator:table
    11  explain select * from t1 union select * from t1;
    12  -- @separator:table
    13  explain select * from t2 union select * from t2;
    14  -- @separator:table
    15  explain select c1 from t1 group by c1;
    16  -- @separator:table
    17  explain select c1 from t2 group by c1;
    18  -- @separator:table
    19  explain select c1,c2 from t2 group by c1,c2;
    20  drop database if exists d1;