planner: refine PhysicalProjection.ResolveIndices during neighbouring Proj

[XuHuaiyu]

Description and test to be added.

What problem does this PR solve?

create table t1(a int, b int);
insert into t1 values(1,1),(2,2);

create table t2(a int, b int);
insert into t2 values(1,1),(2,2);

select sum(c) from (select t1.a as a, t1.a as c, length(t1.b) from t1  union select a, b, b from t2) t;

Before this PR, this query will cause a panic.

What is changed and how it works?

explain info:

+--------------------------------+----------+------+-------------------------------------------------------------+
| id                             | count    | task | operator info                                               |
+--------------------------------+----------+------+-------------------------------------------------------------+
| StreamAgg_16                   | 1.00     | root | funcs:sum(t.c)                                              |
| └─HashAgg_30                   | 16000.00 | root | group by:length(t1.b), t1.a, t1.c, funcs:firstrow(t1.c)     |
|   └─Union_20                   | 20000.00 | root |                                                             |
|     ├─Projection_21            | 10000.00 | root | test.t1.a, test.t1.c, cast(length(t1.b))                    |
|     │ └─Projection_22          | 10000.00 | root | test.t1.a, test.t1.a, length(cast(test.t1.b))               |
|     │   └─TableReader_24       | 10000.00 | root | data:TableScan_23                                           |
|     │     └─TableScan_23       | 10000.00 | cop  | table:t1, range:[-inf,+inf], keep order:false, stats:pseudo |
|     └─Projection_25            | 10000.00 | root | test.t2.a, test.t2.b, cast(test.t2.b)                       |
|       └─TableReader_27         | 10000.00 | root | data:TableScan_26                                           |
|         └─TableScan_26         | 10000.00 | cop  | table:t2, range:[-inf,+inf], keep order:false, stats:pseudo |
+--------------------------------+----------+------+-------------------------------------------------------------+

After buildProjection4Union, Projection_21:test.t1.a.Index and Projection_21:test.t1.c.Index will be 0 and 1 individually.
While both the two Projection_22.test.t1.a.Index are 0.
Thus during execution, when Projection_21:test.t1.c calling chunk.SwapColumn, it will get an empty chunk.column, which would cause the panic.

Check List

Tests

• Integration test

Code changes

• Has exported function/method change

Side effects

Related changes

• Need to cherry-pick to the release branch

release-2.1 release-2.0

[XuHuaiyu]

PTAL @zz-jason

[shenli]

@XuHuaiyu Please fill the description and add a unit test.

[XuHuaiyu]

PTAL @winoros @zz-jason

[XuHuaiyu]

/run-all-tests

[XuHuaiyu]

PTAL @winoros @zz-jason

[XuHuaiyu]

/run-all-tests

[zz-jason]

LGTM

[XuHuaiyu]

To keep the unique of UniqueID, I revert the code, and add some comments for helping understand the logic easily.
@zz-jason @winoros

[winoros]

lgtm

[XuHuaiyu]

/run-all-tests

[zz-jason]

LGTM

[zz-jason]

@XuHuaiyu Please cherrypick this bugfix to the release-2.0 and release-2.1 branch.