feat(planner): implement aggregate operator in new planner framework

[xudong963]

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Summary

• implement aggregate operator in the new planner framework

Changelog

• New Feature

Related Issues

Fixes #3749 #5066

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1 Ignored Deployment

Name	Status	Preview	Updated
databend	⬜️ Ignored (Inspect)		Apr 28, 2022 at 11:09AM (UTC)

[mergify]

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[xudong963]

Currently, the ticket can't produce results due to two known reasons:

1. bug: select can't work in new parser #5044
2. The name style for anonymous select item #5053

But, it's time to review, ensure me on the right road. And if the ticket is ok, I think we can merge it and make it work in next tickets.

[BohuTANG]

Conflicts need resolved :/

[zhang2014]

maybe move .as_any().downcast_ref.ok_or_else into ScalarExprRef is better?

impl ScalarExpr {
    pub fn safe_cast<To>(&self) -> Result<To> {
        self.as_any().downcast_ref::<To>().ok_or_else(|| {...})
    }
}

[xudong963]

Nice idea!

[zhang2014]

unwrap.

[xudong963]

Wow, it works in my local !

mysql> set enable_planner_v2=1;
Query OK, 0 rows affected (0.02 sec)
Read 0 rows, 0 B in 0.002 sec., 0 rows/sec., 0 B/sec.

mysql> select sum(a)  from t group by a;
+----------+
| sum(a_0) |
+----------+
|        1 |
|        2 |
+----------+
2 rows in set (0.04 sec)
Read 2 rows, 8 B in 0.008 sec., 262.05 rows/sec., 1.05 KB/sec.

Will update PR after sorting out code 😄

[BohuTANG]

Some conflicts that must be resolved :D

[xudong963]

Some conflicts that must be resolved :D

Ok, now start to solve conflicts and use enum_dispatch 😆