An index cause SQL ORDER BY can't return correct result
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Key: DERBY-4240
URL: https://issues.apache.org/jira/browse/DERBY-4240
Project: Derby
Issue Type: Bug
Components: SQL
Affects Versions: 10.4.2.0
Reporter: Simon Meng
Following snippet is a SQL example program. It can reproduce a database issue.
DROP TABLE test1;
DROP TABLE test2;
CREATE TABLE test1 (id BIGINT NOT NULL, name VARCHAR(255), PRIMARY KEY (id));
CREATE TABLE test2 (entity_id BIGINT, rel_id BIGINT);
CREATE INDEX idx_test2 ON test2 (entity_id);
INSERT INTO test1 (id, name) VALUES (102, 'Tom');
INSERT INTO test1 (id, name) VALUES (1, null);
INSERT INTO test1 (id, name) VALUES (103, 'Jerry');
INSERT INTO test1 (id, name) VALUES (101, 'Pupy');
INSERT INTO test2 (entity_id, rel_id) VALUES (1, 102);
INSERT INTO test2 (entity_id, rel_id) VALUES (1, 101);
INSERT INTO test2 (entity_id, rel_id) VALUES (1, 103);
SELECT t1.id, t1.name FROM test2 t2 INNER JOIN test1 t1 ON t2.rel_id = t1.id
WHERE t2.entity_id = 1 ORDER BY t1.id ASC;
The expected result should be
ID NAME
--------------------------
101 Pupy
102 Tom
103 Jerry
When running the program, I got below result.
ID NAME
--------------------------
102 Tom
101 Pupy
103 Jerry
The result is obviously wrong. Using ORDER BY ASC does not get expected result.
I found ORDER BY DESC works fine.
Note: there is an index (idx_test2). This index affects the SQL query. If the
index is dropped, ORDER BY ASC can return correct result..
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