The size of column state in tidb_trx is not defined #53026
Description
Bug Report
Please answer these questions before submitting your issue. Thanks!
1. Minimal reproduce step (Required)
create table t(id int);
begin;
insert into t values(1);
select state from information_schema.tidb_trx as trx union select state from information_schema.tidb_trx as trx;
2. What did you expect to see? (Required)
mysql> select state from information_schema.tidb_trx as trx union select state from information_schema.tidb_trx as trx;
+-------+
| state |
+-------+
| Idle |
+-------+
1 row in set (0.00 sec)
3. What did you see instead (Required)
mysql> select state from information_schema.tidb_trx as trx union select state from information_schema.tidb_trx as trx;
+-------+
| state |
+-------+
| |
+-------+
1 row in set, 2 warnings (0.00 sec)
mysql> show warnings;
+---------+------+----------------------------------------+
| Level | Code | Message |
+---------+------+----------------------------------------+
| Warning | 1406 | Data Too Long, field len 0, data len 4 |
| Warning | 1406 | Data Too Long, field len 0, data len 4 |
+---------+------+----------------------------------------+
2 rows in set (0.00 sec)
Because the size of column state in tidb_trx is not defined https://github.com/pingcap/tidb/blob/v6.5.8/infoschema/tables.go#L1466, the cast function uses varchar(0) leading to data too long warning.
mysql> desc select state from information_schema.tidb_trx as trx union select state from information_schema.tidb_trx as trx;
+-----------------------------+----------+------+----------------+----------------------------------------------------------------------------------+
| id | estRows | task | access object | operator info |
+-----------------------------+----------+------+----------------+----------------------------------------------------------------------------------+
| HashAgg_9 | 20000.00 | root | | group by:Column#27, funcs:firstrow(Column#27)->Column#27 |
| └─Union_10 | 20000.00 | root | | |
| ├─Projection_11 | 10000.00 | root | | cast(Column#5, varchar(0) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin)->Column#27 |
| │ └─MemTableScan_12 | 10000.00 | root | table:TIDB_TRX | |
| └─Projection_13 | 10000.00 | root | | cast(Column#18, varchar(0) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin)->Column#27 |
| └─MemTableScan_14 | 10000.00 | root | table:TIDB_TRX | |
+-----------------------------+----------+------+----------------+----------------------------------------------------------------------------------+
6 rows in set (0.00 sec)
4. What is your TiDB version? (Required)
v6.5.8