bit column union Numeric literals select got the wrong results

[aytrack]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

drop table if exists t;
create table t(a bit(20), b float, c double, d int);
insert into t values(10, 10, 10, 10), (1, -1, 2, -2), (2, -2, 1, 1), (2, 1.1, 2.1, 10.1);
select a from t union select 10;

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

mysql> drop table if exists t;
Query OK, 0 rows affected (0.04 sec)

mysql> create table t(a bit(20), b float, c double, d int);
Query OK, 0 rows affected (0.07 sec)

mysql> insert into t values(10, 10, 10, 10), (1, -1, 2, -2), (2, -2, 1, 1), (2, 1.1, 2.1, 10.1);
Query OK, 4 rows affected (0.04 sec)
Records: 4  Duplicates: 0  Warnings: 0

mysql> select a from t union select 10;
+------+
| a    |
+------+
|   10 |
|    1 |
|    2 |
+------+
3 rows in set (0.23 sec)

3. What did you see instead (Required)

mysql> select a from t union select 10;
+----------+
| a        |
+----------+
| 0x00000A |
| 0x3130   |
| 0x000001 |
| 0x000002 |
+----------+
4 rows in set (0.00 sec)

4. What is your TiDB version? (Required)

master: 096281e
release-4.0: 11a9254
release-5.0: e2740f5

[dveeden]

The --column-type-info and --skip-binary-as-hex options of the MySQL client may be useful here.

With MySQL 8.0.22:

mysql> select a from t union select 10;
Field   1:  `a`
Catalog:    `def`
Database:   ``
Table:      ``
Org_table:  ``
Type:       NEWDECIMAL
Collation:  binary (63)
Length:     21
Max_length: 2
Decimals:   0
Flags:      NUM 


+------+
| a    |
+------+
|   10 |
|    1 |
|    2 |
+------+
3 rows in set (0.00 sec)

And with TiDB:

mysql> select a from t union select 10;
Field   1:  `a`
Catalog:    `def`
Database:   ``
Table:      ``
Org_table:  ``
Type:       VAR_STRING
Collation:  binary (63)
Length:     20
Max_length: 3
Decimals:   0
Flags:      NOT_NULL UNSIGNED BINARY 


+----------+
| a        |
+----------+
| 0x00000A |
| 0x3130   |
| 0x000001 |
| 0x000002 |
+----------+
4 rows in set (0.00 sec)

[ti-srebot]

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