pingcap / pingcap/tiflash

Inconsistent cast conversion in Tiflash

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affects-8.4 affects-8.5 component/compute impact/inconsistency may-affects-5.4 may-affects-6.1 may-affects-6.5 may-affects-7.1 may-affects-7.5 may-affects-8.1 severity/major type/bug
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C++
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Beschreibung

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

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  1. Lies das ganze Issue und danach den Beitragsleitfaden des Projekts.
  2. Schreib ins Issue, dass du es übernimmst — das erspart doppelte Arbeit.
  3. Forke das Repository und arbeite in einem Branch.
  4. Öffne einen Pull Request, der die Issue-Nummer nennt.

Rechercherichtung

Beginnen Sie damit, die bereitgestellte SQL-Reproduktion auf TiDB v8.4.0 auszuführen, und vergleichen Sie die TIKV- und TIFLASH-READ_FROM_STORAGE-Ergebnisse für CAST(col1 AS UNSIGNED). Verfolgen Sie die Behandlung des Casts in den beiden Speicherpfaden und konzentrieren Sie sich dabei auf die gezeigten Grenzwerte; die Aufgabe ist abgeschlossen, wenn beide Abfragen konsistente unsigned_int-Ergebnisse liefern.

Vom Indexierungsmodell aus dem Issue-Text verfasst.

Bewertung

Tech-Stack
cpp, sql
Bereich
databases
Issue-Typ
Bug
Schwierigkeit
4/5
Geschätzter Aufwand
3-5 Tage
Aktivitätsstatus
Veraltet
Klarheit
Größtenteils klar
Anfängerfreundlichkeit
35/100

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