Bug #119342 Bits value change after changing UNION to UNION ALL
Submitted: 10 Nov 8:26 Modified: 11 Nov 8:10
Reporter: cl hl Email Updates:
Status: Verified Impact on me:
None 
Category:MySQL Server: Optimizer Severity:S3 (Non-critical)
Version:9.4.0 OS:Any
Assigned to: CPU Architecture:Any

[10 Nov 8:26] cl hl
Description:
after changing UNION to UNION ALL,the c12's value changes unexpectedly

mysql> (SELECT DISTINCT qjn45.c1 AS col_2, qjn45.c12 AS c12 FROM t2 AS qjn45 ORDER BY qjn45.c12 ASC) UNION SELECT ssr75.c4 AS col_2, 98 AS col_3 FROM t1 AS ssr75 UNION SELECT fcb19.c2 AS col_2, fcb19.c9 AS col_3 FROM t2 AS fcb19;
+-------+----------------------------------------------------------+
| col_2 | c12                                                      |
+-------+----------------------------------------------------------+
|   994 | 0x6A                                                     |
|  2340 | 0x8B                                                     |
|  9219 | 0xD7                                                     |
|    90 | 0x3938                                                   |
|    68 | 0x3938                                                   |
|    36 | 0x3938                                                   |
|    48 | 0x3938                                                   |
|    37 | 0x3938                                                   |
|  3423 | 0xCF8CCBA2C880ED9DA9CF8644ECA5BD53E6B0AAED898E10C398D0AD |
|  3423 | 0x1CCFA9                                                 |
|  8711 | 0x37                                                     |
+-------+----------------------------------------------------------+
11 rows in set (0.00 sec)

mysql> (SELECT DISTINCT qjn45.c1 AS col_2, qjn45.c12 AS c12 FROM t2 AS qjn45 ORDER BY qjn45.c12 ASC) UNION SELECT ssr75.c4 AS col_2, 98 AS col_3 FROM t1 AS ssr75 UNION ALL SELECT fcb19.c2 AS col_2, fcb19.c9 AS col_3 FROM t2 AS fcb19;
+-------+----------------------------------------------------------+
| col_2 | c12                                                      |
+-------+----------------------------------------------------------+
|   994 | 0x313036                                                 |
|  2340 | 0x313339                                                 |
|  9219 | 0x323135                                                 |
|    90 | 0x3938                                                   |
|    68 | 0x3938                                                   |
|    36 | 0x3938                                                   |
|    48 | 0x3938                                                   |
|    37 | 0x3938                                                   |
|  3423 | 0xCF8CCBA2C880ED9DA9CF8644ECA5BD53E6B0AAED898E10C398D0AD |
|  3423 | 0x1CCFA9                                                 |
|  8711 | 0x37                                                     |
+-------+----------------------------------------------------------+
11 rows in set (0.00 sec)

How to repeat:
DROP DATABASE IF EXISTS test;
CREATE DATABASE IF NOT EXISTS test;
USE test;
CREATE TABLE t1 (
    c1 INT NOT NULL AUTO_INCREMENT,
    c2 VARCHAR(255) NOT NULL,
    c3 VARCHAR(255) NULL,
    c4 INT NULL,
    c5 DATE NOT NULL,
    c6 VARCHAR(10) NOT NULL,
    PRIMARY KEY (c1)
);

CREATE TABLE t2 (
    c1 INT NOT NULL AUTO_INCREMENT,
    c2 INT NOT NULL,
    c3 DECIMAL(10,2) NOT NULL,
    c4 VARCHAR(50) NOT NULL,
    c5 DATE NOT NULL,
    c6 MEDIUMTEXT NULL,
    c7 LONGTEXT NULL,
    c8 MEDIUMBLOB NULL,
    c9 LONGBLOB NULL,
    c10 ENUM('value1','value2','value3') NULL,
    c11 SET('a','b','c','d') NULL,
    c12 BIT(8) NULL,
    c13 DATETIME NULL,
    c14 FLOAT(8,2) NULL,
    c15 DOUBLE(12,4) NULL,
    PRIMARY KEY (c1)
);

INSERT INTO t1 (c1, c2, c3, c4, c5, c6) VALUES (3584, 'sample_AQJP3FCb7PX46hF2d3VoKsPIHtIgzieVgOK1Ue7iSbNProjjh', 'sample_v', 36, '2025-09-07', 'sample_J');
INSERT INTO t1 (c1, c2, c3, c4, c5, c6) VALUES (954, 'sample_0kfPnPKeUjkycwqHxj5OtQ8', 'sample_sQ', 90, '2025-10-10', 'sample_C');
INSERT INTO t1 (c1, c2, c3, c4, c5, c6) VALUES (1986, 'sample_tJaorTY4zIEBbb8IM4auYieeVSd80foFpJh3MIv0Rz8fEgfYthMyHLdUMnlIN6NnP0VoAFBpSEUcHovYpCFbGrC98Y52vXpgXsmsEBDYj6ecgN2JkDh393f4hhIjFLpqffJrE5Z09WtyvK6PT0IcDNjF6S16yhunjPWFxaAbK4Z6', 'sample_bIa5736UIVD92z8u5rQ0PaRpPlOEwroZ4Xoqc4jDp4SiRROqU4u2EvOZZupAHmFPuFcWjOC6V16yTz58i3824l1EdwAgMPAPy9RM2sHerAB3L3eAWFGFd', 68, '2025-04-20', 'sample_KWK');
INSERT INTO t1 (c1, c2, c3, c4, c5, c6) VALUES (6432, 'sample_apUxsuYxJ7yJ6etwr3Sd7Cg7l1JHXVRSgSUF689u4w2greqF3zbivycDbv6qA4Wusopmd80qoDFLGg1ercUJBRyEl0j0aw1JXgj35Pg4JK2lNYBG2UPKBvS3jhsYpkYbhUNtq5zfTal0MXOuOk4CydQWObucwCG1tGcBtxVHzwZf18W2M7Fl2c8AzYVIIn', 'sample_xoju7XvqD9RJhJ2NAoI2KxR5QZdZKDIjrOdN8MahX1k3dJu9UxKIjMzLtBjiMnoN5JxDvSR7bHNsAECcv5onlaOPg4TBQg4yQw6ThZm8lvYZcq9lBqZap4SoxgEZLdQaIflJvl7EcmCUqqRgQEes', 48, '2025-04-28', 'sample_N');
INSERT INTO t1 (c1, c2, c3, c4, c5, c6) VALUES (8644, 'sample_IYRIsvectgAbcVIlfnvNd9kX3FNkOo4kAKKY1BDBLFQpH7ksvMtBllsZK16dP8T7twvH59dyaLTQuKIciaq8hnHB49XU7pS4kDw8Gt9mASD1ylSfvFBVtDNT', 'sample_7K12anyKLHlFNF5tfck9rj0CREpw10By71a2xm7uMRqIH61pLHnO3mXiWV0Ql013c5vK', 37, '2024-11-16', 'sample_8');

INSERT INTO t2 (c1, c2, c3, c4, c5, c6, c7, c8, c9, c10, c11, c12, c13, c14, c15) VALUES (994, 3423, 181.05, 'sample_wfxp8dzD7XrFnPLzr', '2024-12-16', 'sample_pVtuVRHgHyCTAdMjTX5uDmgDFTTcRtYK4MA3VzWGhxyRAthAan095ltHnWC2wZqFzmNIz2BhrrY2h0fxo8UzijtqT3Qzyc7ydCZ760AbwzyWxKRhxPNIiXBNmglw9ylwoKoF0Q5QMAuWKKHLT07TyALEjZEq9SXDPPHZkG637npBmt2TKOxONpcXFVVrsW3jgaSAVhmwZMYON8YAyhzkhs0fsDZAohNdcrXeb43HI5de5EWnnY2lj8xyjRyfvWyVnBrhfeRiVnwUHuk0bcwoN3ueyVTRnXwQSF56ZbxUsw4hUmzUQ4GGRNJqlHOzrdMFLZHnsp5SamGZ0WPFJC1Vx1RuAnB5RdThXSIL8o2Fgebw5VIlETIWBvsuSQqrlbUxl0DbKa4xwcIiP23T8cVxdUgU4xKNvx6nab1kO47gdMcGoSGyXyvr23yKaVpjtw6XNe0uwE6zNt4nqZ1IMHxo', 'sample_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', X'4DD6A6D687C6A9C08CDA93E9B48429DAA8ECBF93E891B67DDEBCDEBCE79C8A20', X'CF8CCBA2C880ED9DA9CF8644ECA5BD53E6B0AAED898E10C398D0AD', 'value1', 'a,c,b,d', b'01101010', '2025-04-25 18:28:30', 90.91, 53.96);
INSERT INTO t2 (c1, c2, c3, c4, c5, c6, c7, c8, c9, c10, c11, c12, c13, c14, c15) VALUES (9219, 8711, 166.61, 'sample_b7C1trecK6yntdY4x3tkM8epFQtYVnoEfz17wiJ0h80', '2025-04-12', 'sample_lM7ywI1JmA9kqk0PwSZZlxesXZdCBedJvwYKBw9dR56w7WO7DzbB1ZVsW2uBiEHEd2wR0zfA4sx55xrLO89GGMf4F2mz0UofYA4LoqJgyFeasOQ0xqixQuPntbtFFaU0qHyeuRqR7GpKm67SSQeJQd5eZ7q71APzN3n0zFxL9bC0jVQUAA2zi4LuWSd0Py4RHM12FEZBN1KuHU5ZozMhLHirnlRKFd0CHuHyUguieTnEjt89dxMMgaDrETZaKHVR1ScgTZefc8hb2Y5a2zsDfzRCQbzUBuZhyxWPDkLMg5eJaLJRAGHMN71OJrpgGZCWwFkmvr3GquST0vH8CnT59cLY9O9v9udhzAtGCiQXbwB5Lj7KzeYHgjKr8X09e6EGFI4JxrFhFkCd8iyB8xSq8NysRpDP91m9AphkU', 'sample_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', X'3E00CE8341C791EE918038EE949521C58A15D0B301D3BBE09EADEBBDA75BE890B0D58D53', X'37', 'value1', 'c,b,a', b'11010111', '2025-01-23 17:58:04', 97.71, 79.57);
INSERT INTO t2 (c1, c2, c3, c4, c5, c6, c7, c8, c9, c10, c11, c12, c13, c14, c15) VALUES (2340, 3423, 789.64, 'sample_JtpdkPugJClf6wBGA48lgU0DFFQny1d', '2025-01-19', 'sample_7R6EMmsSUYkMz6YCdnJKFiZabj1AjoceqELoBIvttyuANntWJL2Iguil0ggBEhhicCIyajZZCbnYcoia8z8m2xhobdtGwkvfOFQCJYstbgEOwNRMKP3JikRrYTGn6M16dllazrq68Ih1EE6ZgTAYVDzjsMXfYMHELWNupyYn5JJzpScnf9xkHTtu4IoNR4WeVzHt1nzkrI8VhXULipuUH1s9gmSc8Pean8HlBr9tXw2vG5E0N04ZbCricxniIf4xVAEc7Q8n7hVRH58ZsdYOhX', 'sample_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', X'E4B6A42FC3B5E9B69AD0A3EB9DA6EF81A0', X'1CCFA9', 'value3', 'c,b', b'10001011', '2025-03-23 19:05:28', 76.33, 87.70);

(SELECT DISTINCT qjn45.c1 AS col_2, qjn45.c12 AS c12 FROM t2 AS qjn45 ORDER BY qjn45.c12 ASC) UNION SELECT ssr75.c4 AS col_2, 98 AS col_3 FROM t1 AS ssr75 UNION SELECT fcb19.c2 AS col_2, fcb19.c9 AS col_3 FROM t2 AS fcb19;
(SELECT DISTINCT qjn45.c1 AS col_2, qjn45.c12 AS c12 FROM t2 AS qjn45 ORDER BY qjn45.c12 ASC) UNION SELECT ssr75.c4 AS col_2, 98 AS col_3 FROM t1 AS ssr75 UNION ALL SELECT fcb19.c2 AS col_2, fcb19.c9 AS col_3 FROM t2 AS fcb19;
[11 Nov 8:10] Roy Lyseng
Verified as described.