query partition table with global unique index get wrong result

[crazycs520]

Development Task

Related issue: #18032

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

TiDB config:

enable-global-index=true

create table t (a int, b int GENERATED ALWAYS AS (3*a-2*a) VIRTUAL) partition by hash(b) partitions 2;
alter table t add unique index idx (a);
insert into t (a) values  (1),(2),(3);
select * from t ignore index (idx);
select * from t use index (idx);

2. What did you expect to see? (Required)

test> select * from t use index (idx);
+---+---+
| a | b |
+---+---+
| 2 | 2 |
| 1 | 1 |
| 3 | 3 |
+---+---+

3. What did you see instead (Required)

test> select * from t use index (idx);
+---+---+
| a | b |
+---+---+
0 rows in set
Time: 0.014s

4. What is your TiDB version? (Required)

test> select tidb_version();
+-------------------------------------------------------------------+
| tidb_version()                                                    |
+-------------------------------------------------------------------+
| Release Version: v4.0.0-beta.2-1812-gd33b81b1e                    |
| Edition: Community                                                |
| Git Commit Hash: d33b81b1ee69bd60a56e45f87774e76014720a6e         |
| Git Branch: master                                                |
| UTC Build Time: 2020-12-14 12:59:19                               |
| GoVersion: go1.14.4                                               |
| Race Enabled: false                                               |
| TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306 |
| Check Table Before Drop: false                                    |
+-------------------------------------------------------------------+

[crazycs520]

@tiancaiamao PTAL

[ichn-hu]

/assign @tiancaiamao

[tiancaiamao]

I've removed the severity/critical label as the global index is not a released feature yet.

And I've changed the issue template to 'development task' instead of 'bug report'

[mjonss]

/component tablepartition