Import into ... from select does not comply with the current SQL mode

[gengliqi]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

mysql> create table t(a double);
Query OK, 0 rows affected (0.08 sec)

mysql> create table s(x varchar(20));
Query OK, 0 rows affected (0.08 sec)

mysql> insert into s values('1e309abc');
Query OK, 1 row affected (0.01 sec)

mysql> alter table s set tiflash replica 1;
Query OK, 0 rows affected (0.11 sec)

mysql> set tidb_enforce_mpp=1;
Query OK, 0 rows affected (0.00 sec)

mysql> set sql_mode='';
Query OK, 0 rows affected (0.00 sec)

mysql> insert into t select cast(x as double) from s;
Query OK, 1 row affected (0.09 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> truncate t;
Query OK, 0 rows affected (0.08 sec)

mysql> import into t from select cast(x as double) from s;
ERROR 1105 (HY000): other error for mpp stream: Code: 0, e.displayText() = DB::TiFlashException: Overflow error: Truncated incorrect DOUBLE value, e.what() = DB::TiFlashException,
mysql> explain import into t from select cast(x as double) from s;
+------------------------------+----------+--------------+---------------+-----------------------------------------+
| id                           | estRows  | task         | access object | operator info                           |
+------------------------------+----------+--------------+---------------+-----------------------------------------+
| ImportInto_2                 | N/A      | root         |               | N/A                                     |
| └─TableReader_14             | 10000.00 | root         |               | MppVersion: 2, data:ExchangeSender_13   |
|   └─ExchangeSender_13        | 10000.00 | mpp[tiflash] |               | ExchangeType: PassThrough               |
|     └─Projection_6           | 10000.00 | mpp[tiflash] |               | cast(test.s.x, double BINARY)->Column#4 |
|       └─TableFullScan_12     | 10000.00 | mpp[tiflash] | table:s       | keep order:false, stats:pseudo          |
+------------------------------+----------+--------------+---------------+-----------------------------------------+
5 rows in set (0.00 sec)

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

The sql import into ... from select should use non-strict sql mode and run successfully.

3. What did you see instead (Required)

Run failed

4. What is your TiDB version? (Required)

v8.1.1

[D3Hunter]

there are some difference in MPP flags, but the flag for import into(0b110000001) in DAGRequest already contains FlagIgnoreTruncate uint64 = 1.

if we run import into with TiKV(without run the tiflash replica statement), it works, it seems tiflash doesn't honor FlagIgnoreTruncate as tikv does. created a tiflash issue pingcap/tiflash#9752

[windtalker]

The root cause is TiFlash's error handling logic is the same earlier version of TiDB, which treat overflow and truncate as different error, but after #49122, there is actually no overflow error, the OVERFLOW_AS_WARNING flag is useless, but TiFlash still use this to handle the overflow error.