Inconsistent cast conversion in Tiflash

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

Drop table if exists test_table;
CREATE TABLE test_table (
    id INT PRIMARY KEY AUTO_INCREMENT,
    col1 VARCHAR(255),
    col2 TINYINT,
    col3 SMALLINT
);

INSERT INTO test_table (col1, col2, col3) VALUES
    ('-9223372036854775809', -128, -32768),
    ('-9223372036854775808', 127, 32767);

ALTER TABLE test_table SET TIFLASH REPLICA 1;

SELECT /*+ READ_FROM_STORAGE(TIKV[test_table])*/
    id,
    col1,
    CAST(col1 AS SIGNED) AS signed_int,
    CAST(col1 AS UNSIGNED) AS unsigned_int,
    CAST(col1 AS DECIMAL(65,30)) AS decimal_value,
    CAST(col1 AS DOUBLE) AS double_value
FROM
    test_table;
    
SELECT /*+ READ_FROM_STORAGE(TIFLASH[test_table])*/
    id,
    col1,
    CAST(col1 AS SIGNED) AS signed_int,
    CAST(col1 AS UNSIGNED) AS unsigned_int,
    CAST(col1 AS DECIMAL(65,30)) AS decimal_value,
    CAST(col1 AS DOUBLE) AS double_value
FROM
    test_table;

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

I find that unsigned_int is inconsistent across two queries.

3. What did you see instead (Required)

mysql> SELECT /*+ READ_FROM_STORAGE(TIKV[test_table])*/
    ->     id,
    ->     col1,
    ->     CAST(col1 AS SIGNED) AS signed_int,
    ->     CAST(col1 AS UNSIGNED) AS unsigned_int,
    ->     CAST(col1 AS DECIMAL(65,30)) AS decimal_value,
    ->     CAST(col1 AS DOUBLE) AS double_value
    -> FROM
    ->     test_table;
+----+----------------------+----------------------+---------------------+-----------------------------------------------------+-----------------------+
| id | col1                 | signed_int           | unsigned_int        | decimal_value                                       | double_value          |
+----+----------------------+----------------------+---------------------+-----------------------------------------------------+-----------------------+
|  1 | -9223372036854775809 | -9223372036854775808 | 9223372036854775808 | -9223372036854775809.000000000000000000000000000000 | -9.223372036854776e18 |
|  2 | -9223372036854775808 | -9223372036854775808 | 9223372036854775808 | -9223372036854775808.000000000000000000000000000000 | -9.223372036854776e18 |
+----+----------------------+----------------------+---------------------+-----------------------------------------------------+-----------------------+
2 rows in set, 4 warnings (0.01 sec)

mysql> SELECT /*+ READ_FROM_STORAGE(TIFLASH[test_table])*/     id,     col1,     CAST(col1 AS SIGNED) AS signed_int,     CAST(col1 AS UNSIGNED) AS unsigned_int,     CAST(col1 AS DECIMAL(65,30)) AS decimal_value,     CAST(col1 AS DOUBLE) AS double_value FROM
  test_table;
+----+----------------------+----------------------+---------------------+-----------------------------------------------------+-----------------------+
| id | col1                 | signed_int           | unsigned_int        | decimal_value                                       | double_value          |
+----+----------------------+----------------------+---------------------+-----------------------------------------------------+-----------------------+
|  1 | -9223372036854775809 | -9223372036854775808 |                   0 | -9223372036854775809.000000000000000000000000000000 | -9.223372036854776e18 |
|  2 | -9223372036854775808 | -9223372036854775808 | 9223372036854775808 | -9223372036854775808.000000000000000000000000000000 | -9.223372036854776e18 |
+----+----------------------+----------------------+---------------------+-----------------------------------------------------+-----------------------+
2 rows in set (0.01 sec)

4. What is your TiDB version? (Required)

TiDB v8.4.0

まず、提供されたSQL再現をTiDB v8.4.0で実行し、CAST(col1 AS UNSIGNED)に対するTIKVとTIFLASH-READ_FROM_STORAGEの結果を比較します。示されている境界値に注目しながら、2つのストレージパスでのcast処理を追跡します。両方のクエリが一貫したunsigned_int結果を生成すれば完了です。