planner: don't reset optFlag when build DataSource from View

[francis0407]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do?

mysql> create table pt (a int primary key, b int)
 partition by range (a)
 (partition p0 values less than(10), 
partition p1 values less than(20), 
partition p2 values less than(30));
Query OK, 0 rows affected (0.04 sec)

mysql> insert into pt values(1, 1), (11, 11), (21, 21);

mysql> select * from t;
+------+------+
| a    | b    |
+------+------+
|    1 |    1 |
+------+------+
1 row in set (0.00 sec)
Query OK, 3 rows affected (0.01 sec)
Records: 3  Duplicates: 0  Warnings: 0

mysql> create view vt (a, b) as select a, b from t;
Query OK, 0 rows affected (0.00 sec)

mysql> select * from pt, t where pt.a < 10 and pt.b = t.b;
+---+------+------+------+
| a | b    | a    | b    |
+---+------+------+------+
| 1 |    1 |    1 |    1 |
+---+------+------+------+
1 row in set (0.01 sec)

mysql> select * from pt, vt where pt.a < 10 and pt.b = vt.b;
Empty set (0.00 sec)

2. What did you expect to see?

The two queries above should have the same result 1, 1, 1, 1.

3. What did you see instead?

When we use the view vt, the result set is empty.

4. What version of TiDB are you using? (tidb-server -V or run select tidb_version(); on TiDB)

4.0-beta

[francis0407]

The root cause is when we build DataSource from a View, we reset the optFlag.