[MDEV-8639] Bad result set when using prefix keys and characters less than space Created: 2015-08-18  Updated: 2022-12-15

Status: Confirmed
Project: MariaDB Server
Component/s: Character Sets
Affects Version/s: 5.5, 10.0, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 10.10
Fix Version/s: 10.1, 10.3

Type: Bug Priority: Minor
Reporter: Alexander Barkov Assignee: Alexander Barkov
Resolution: Unresolved Votes: 0
Labels: None


 Description   

This script correctly returns one row:

DROP TABLE IF EXISTS t1;
 
CREATE TABLE t1 (a VARCHAR(10) CHARACTER SET latin1);
 
INSERT INTO t1 VALUES ('a'),('a\t'),('az'),('b'),('c'),('d'),('e');
 
SELECT * FROM t1 WHERE a<'a';
 

+------+
 
| a    |
 
+------+
 
| a	   |
 
+------+
 
1 row in set (0.00 sec)

Now if I add a prefix index and re-run the select query:

ALTER TABLE t1 ADD KEY a(a(1));
 
SELECT * FROM t1 WHERE a<'a';

it erroneously returns empty set.
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