Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Fixed
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5.3.12, 5.5.34, 10.0.6
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None
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None
Description
(Thanks to shad0w1e on Freenode #mysql for finding this bug. I reduced it to a minimal test case and figured out the affected versions.)
The following will crash MariaDB. MySQL is not similarly affected:
DROP TABLE IF EXISTS `t1`;
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CREATE TABLE `t1` (
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`a` INT DEFAULT NULL
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);
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DROP TABLE IF EXISTS `t2`;
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CREATE TABLE `t2` (
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`b` INT DEFAULT NULL
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);
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# No crash:
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SET SESSION optimizer_switch='derived_merge=OFF';
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SELECT c1
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FROM (
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SELECT (
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SELECT 1
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FROM t1
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WHERE t1.a <= t2.b
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UNION ALL
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SELECT 1
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FROM t1
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WHERE t1.a <= t2.b
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ORDER BY a DESC
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) AS c1
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FROM t2
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) t3;
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# Crash:
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SET SESSION optimizer_switch='derived_merge=ON';
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|
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SELECT c1
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FROM (
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SELECT (
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SELECT 1
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FROM t1
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WHERE t1.a <= t2.b
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UNION ALL
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SELECT 1
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FROM t1
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WHERE t1.a <= t2.b
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ORDER BY a DESC
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) AS c1
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FROM t2
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) t3;
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