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This script:
DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (a VARCHAR(10) COLLATE latin1_bin);
INSERT INTO t1 VALUES ('a'),('a ');
SELECT a, LENGTH(a) FROM t1 WHERE a NOT LIKE 'a ';
returns one row:
+------+-----------+ | a | LENGTH(a) | +------+-----------+ | a | 1 | +------+-----------+
Now if I make the condition even stronger:
SELECT a, LENGTH(a) FROM t1 WHERE a NOT LIKE 'a ' AND a='a';
it erroneously returns 2 rows:
+------+-----------+ | a | LENGTH(a) | +------+-----------+ | a | 1 | | a | 2 | +------+-----------+
The problem happens in equal fields propagation.
WHERE a NOT LIKE 'a ' AND a='a'
gets rewritten to
WHERE 'a' NOT LIKE 'a ' AND a='a'
then LIKE gets removed from the condition.
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MDEV-8728 Fix a number of problems in equal field and equal expression propagation
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