chore: support planner_v2 in documentation

Signed-off-by: Fedomn <[email protected]>

README.md

@@ -7,15 +7,20 @@ sqlrs is an in-process sql query engine that designed for OLAP
 - It achieved columnar-vectorized execution engine.
 - It will support pipeline parallelism execution in the future.
 
+🚧 The project is actively developing a new planner V2 that inspired by DuckDB, and will replace the planner v1 in the future.🚧 
+
 # SQL demo
 
-currently, the following SQL statements are supported, execute `make run` into interactive mode to test them:
+currently, the following SQL statements are supported, execute the commands into interactive mode to test them:
+
+- `make run`: run sqlrs in planner_v1
+- `make run_v2`: run sqlrs in planner_v2
 
 ```sql
--- supported in Roadmap 0.1
+-- supported in Roadmap 0.1 (planner_v1)
 select first_name from employee where last_name = 'Hopkins';
 
--- supported in Roadmap 0.2
+-- supported in Roadmap 0.2 (planner_v1)
 select sum(salary+1), count(salary), max(salary) from employee where id > 1;
 select state, count(state), sum(salary) from employee group by state;
 -- load csv table
@@ -24,16 +29,16 @@ select state, count(state), sum(salary) from employee group by state;
 -- show tables
 \dt
 
--- supported in Roadmap 0.3
+-- supported in Roadmap 0.3 (planner_v1)
 select id from employee order by id desc offset 2 limit 1;
 select * from employee left join state on employee.state=state.state_code and state.state_name!='California State';
 
--- supported in Roadmap 0.4
+-- supported in Roadmap 0.4 (planner_v1)
 -- explain plan tree
 \explain select a from t1;
 -- Heuristic Optimizer that includes rules such as: Column pruning, Predicates pushdown, Limit pushdown etc.
 
--- supported in Roadmap 0.5
+-- supported in Roadmap 0.5 (planner_v1)
 -- distinct
 select distinct state from employee;
 select count(distinct(b)) from t2;
@@ -43,6 +48,21 @@ select t.a from t1 t where t.b > 1 order by t.a desc limit 1;
 -- uncorrelated scalar subquery
 select t.* from (select * from t1 where a > 1) t where t.b > 7;
 select a, (select max(b) from t1) max_b from t1;
+
+
+-- supported in Roadmap 0.6 (planner_v2)
+-- create and insert table in memory
+create table t1(v1 int, v2 int, v3 int);
+insert into t1 values (0, 4, 1), (1, 5, 2);
+select * from t1;
+-- select only expressions
+select 1, 2.3, '😇', true, null;
+-- pragma commands
+show tables;
+describe t1;
+-- previous SQL statements
+select v1+1 as a from t1 where a >= 2;
+select v1 from t1 limit 2 offset 1;
 ```
 
 
@@ -54,6 +74,8 @@ High level description:
 - Roadmap 0.2: Support aggregation operators, e2e testing framework and interactive mode
 - Roadmap 0.3: Support limit, order, and join operators
 - Roadmap 0.4: Introduce a Heuristic Optimizer and common optimization rules
+- Roadmap 0.5: Support distinct, alias, and uncorrelated scalar subquery
+- Roadmap 0.6: New planner_v2 highly inspired by DuckDB
 
 Please see [Roadmap](https://github.com/Fedomn/sqlrs/issues?q=roadmap) for more information of implementation steps