feat(planner): Support select operator in new planner framework

[leiysky]

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Summary

Support WHERE clause in new planner.

Should be merged after #5058

Changelog

• New Feature

Related Issues

Related to #3747

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Name	Status	Preview	Updated
databend	✅ Ready (Inspect)	Visit Preview	Apr 26, 2022 at 11:45AM (UTC)

[mergify]

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[xudong963]

👍，it works for some cases

mysql> select * from t;
+------+
| a    |
+------+
|    1 |
|    2 |
+------+
2 rows in set (0.07 sec)
Read 2 rows, 8 B in 0.019 sec., 103.73 rows/sec., 414.93 B/sec.

mysql> select a from t where a = 1;
ERROR 1105 (HY000): Code: 1002, displayText = Unsupported expr: Literal(Number("1")).
mysql> select a from t where a = a;
+------+
| a    |
+------+
|    1 |
|    2 |
+------+
2 rows in set (0.04 sec)
Read 2 rows, 8 B in 0.006 sec., 346.2 rows/sec., 1.38 KB/sec.

[xudong963]

Why do we need to match the op here, can't we just leave it to Expression?

--- a/query/src/sql/planner/binder/scalar.rs
+++ b/query/src/sql/planner/binder/scalar.rs
@@ -64,16 +64,10 @@ impl ScalarBinder {
     ) -> Result<ScalarExprRef> {
         let left_scalar = self.bind_expr(left_child, bind_context)?;
         let right_scalar = self.bind_expr(right_child, bind_context)?;
-        match op {
-            BinaryOperator::Eq => Ok(Arc::new(Scalar::Equal {
-                left: left_scalar,
-                right: right_scalar,
-            })),
-            _ => Err(ErrorCode::UnImplement(format!(
-                "Unsupported binary operator: {}",
-                op.to_string()
-            ))),
-        }
+        Ok(Arc::new(Scalar::Binary {
+            left: left_scalar,
+            right: right_scalar,
+        }))
     }
 }

Then other ops will be supported

mysql> set enable_planner_v2=1;
No connection. Trying to reconnect...
Connection id:    8
Current database: *** NONE ***

Query OK, 0 rows affected (0.56 sec)
Read 0 rows, 0 B in 0.537 sec., 0 rows/sec., 0 B/sec.

mysql> select * from t;
+------+
| a    |
+------+
|    1 |
|    2 |
+------+
2 rows in set (0.06 sec)
Read 2 rows, 8 B in 0.017 sec., 115.6 rows/sec., 462.41 B/sec.

mysql> select a from t where a <= a;
+------+
| a    |
+------+
|    1 |
|    2 |
+------+
2 rows in set (0.04 sec)
Read 2 rows, 8 B in 0.005 sec., 378.62 rows/sec., 1.51 KB/sec.

[leiysky]

Some binary operators have useful property, I'd like to make them typed.

More scalar expressions would be supported later.

[xudong963]

The useful property will be used in the optimizer?

[leiysky]

Yes, for instance cardinality estimation.

[xudong963]

LGTM

[mergify]

Thanks for the contribution!
I have applied any labels matching special text in your PR Changelog.

Please review the labels and make any necessary changes.