Stefan Zeiger created DERBY-5911:
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Summary: WHERE condition getting pushed into sub-query with FETCH
Key: DERBY-5911
URL: https://issues.apache.org/jira/browse/DERBY-5911
Project: Derby
Issue Type: Bug
Components: SQL
Affects Versions: 10.9.1.0
Environment: Tested with Derby 10.9.1.0 on Windows 7 x64, Java
1.6.0_27-b07 server
Reporter: Stefan Zeiger
Derby pushes query conditions down into subqueries with FETCH limits, thus
creating wrong results. Take the following snippet:
CREATE TABLE COFFEES (COF_NAME VARCHAR(254),PRICE INTEGER);
INSERT INTO COFFEES (COF_NAME,PRICE) VALUES ('Colombian', 5);
INSERT INTO COFFEES (COF_NAME,PRICE) VALUES ('French_Roast', 5);
INSERT INTO COFFEES (COF_NAME,PRICE) VALUES ('Colombian_Decaf', 20);
select COF_NAME, PRICE from COFFEES order by COF_NAME fetch next 2 rows
only;
select * from (
select COF_NAME, PRICE from COFFEES order by COF_NAME fetch next 2 rows
only
) t where t.PRICE < 10;
The first query correctly returns the rows (Colombian,5), (Colombian_Decaf,20).
The second query (which filters the result of the first one) returns
(Colombian,5), (French_Roast,5). The row (French_Roast,5) should not be there
since it is not a result of the first query. It shows up because (supposedly)
the filter condition has been evaluated before the fetch limit.
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