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Description:
In theory, the result of sql2(DISTINCT) ⊆ the result of sql1:
SELECT ~f1 FROM (SELECT (DATE_ADD(REPEAT(c1, 3), INTERVAL 1 MINUTE_MICROSECOND)) AS f1 FROM t) AS t1; -- sql1
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SELECT ~f1 FROM (SELECT DISTINCT (DATE_ADD(REPEAT(c1, 3), INTERVAL 1 MINUTE_MICROSECOND)) AS f1 FROM t) AS t1; -- sql2
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However, the value 18446744063608551615 changed to 18446744073709551614 after adding DISTINCT, seems like a logical bug:
mysql> select version();
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+-----------------------------------------+
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| version() |
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+-----------------------------------------+
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| 10.11.1-MariaDB-1:10.11.1+maria~ubu2204 |
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+-----------------------------------------+
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1 row in set (0.00 sec)
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mysql> SELECT ~f1 FROM (SELECT (DATE_ADD(REPEAT(c1, 3), INTERVAL 1 MINUTE_MICROSECOND)) AS f1 FROM t) AS t1; -- sql1
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+----------------------+
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| ~f1 |
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+----------------------+
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| 18446744063608551615 |
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+----------------------+
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1 row in set (0.00 sec)
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mysql> SELECT ~f1 FROM (SELECT DISTINCT (DATE_ADD(REPEAT(c1, 3), INTERVAL 1 MINUTE_MICROSECOND)) AS f1 FROM t) AS t1; -- sql2
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+----------------------+
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| ~f1 |
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+----------------------+
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| 18446744073709551614 |
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+----------------------+
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1 row in set, 1 warning (0.00 sec)
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How to repeat:
drop table if exists t;
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CREATE TABLE t (c1 DECIMAL(40,20));
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INSERT INTO t VALUES (1);
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SELECT ~f1 FROM (SELECT (DATE_ADD(REPEAT(c1, 3), INTERVAL 1 MINUTE_MICROSECOND)) AS f1 FROM t) AS t1; -- sql1
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SELECT ~f1 FROM (SELECT DISTINCT (DATE_ADD(REPEAT(c1, 3), INTERVAL 1 MINUTE_MICROSECOND)) AS f1 FROM t) AS t1; -- sql2
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Hope these can be helpful for your debugging:
1. The bug cannot be reproduced after changing REPEAT(c1, 3) to REPEAT(c1, 2);
2. The bug cannot be reproduced after changing MINUTE_MICROSECOND to SECOND;
3. We look for the first version of the bug in all docker images (with format x.x.x) of https://hub.docker.com/_/mariadb/tags
We found that the bug first occurred in mariadb:10.0.15, it cannot be reproduced in mariadb:5.5.64 (we can't find more intermediate versions in dockerhub):
MariaDB [TEST]> select version();
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+------------------------------+
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| version() |
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+------------------------------+
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| 10.0.15-MariaDB-1~wheezy-log |
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+------------------------------+
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1 row in set (0.00 sec)
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MariaDB [TEST]> SELECT ~f1 FROM (SELECT (DATE_ADD(REPEAT(c1, 3), INTERVAL 1 MINUTE_MICROSECOND)) AS f1 FROM t) AS t1; -- sql1
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+----------------------+
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| ~f1 |
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+----------------------+
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| 18446744063608551615 |
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+----------------------+
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1 row in set (0.00 sec)
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MariaDB [TEST]> SELECT ~f1 FROM (SELECT DISTINCT (DATE_ADD(REPEAT(c1, 3), INTERVAL 1 MINUTE_MICROSECOND)) AS f1 FROM t) AS t1; -- sql2
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+----------------------+
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| ~f1 |
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+----------------------+
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| 18446744073709551614 |
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+----------------------+
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1 row in set, 1 warning (0.00 sec)
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MariaDB [TEST]> select version();
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+-------------------------+
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| version() |
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+-------------------------+
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| 5.5.64-MariaDB-1~trusty |
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+-------------------------+
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1 row in set (0.00 sec)
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MariaDB [TEST]> SELECT ~f1 FROM (SELECT (DATE_ADD(REPEAT(c1, 3), INTERVAL 1 MINUTE_MICROSECOND)) AS f1 FROM t) AS t1; -- sql1
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+------+
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| ~f1 |
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+------+
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| NULL |
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+------+
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1 row in set, 2 warnings (0.00 sec)
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MariaDB [TEST]> SELECT ~f1 FROM (SELECT DISTINCT (DATE_ADD(REPEAT(c1, 3), INTERVAL 1 MINUTE_MICROSECOND)) AS f1 FROM t) AS t1; -- sql2
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+------+
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| ~f1 |
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+------+
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| NULL |
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+------+
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1 row in set, 2 warnings (0.00 sec)
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