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https://issues.apache.org/jira/browse/DERBY-3231?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12550551
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A B commented on DERBY-3231:
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> The problem was missing methods isConstant and isConstantExpression for
> AggregateNodes. The super class implementation would return true causing
> Derby to eliminate the order by.
Thank you for looking into this, Manish! Two follow-up questions based on what
you have found, just for my own understanding:
1) If possible, can you explain what part of the DERBY-681 changes led to
this behavior, since the query returned correct results prior to the DERBY-681
fix? I'm just curious as to why the missing methods for AggregateNode were not
a problem previously.
2) Any idea why removing the "WHERE" clause from the original query causes it
to return correct results, even without the order_by_bug.diff patch, as stated
in your December 4th comment? I admit I haven't done any tracing myself, but
from your previous comment I can't quite see the connection between the WHERE
clause and the ORDER BY, since the WHERE clause does not reference the
aggregate "count(*)". Apologies if I'm missing something obvious...
Thanks again for your willingness to investigate this further. Have you had a
chance to run any of the regression tests with your patch applied?
> Sorting on COUNT with OR and GROUP BY delivers wrong results.
> -------------------------------------------------------------
>
> Key: DERBY-3231
> URL: https://issues.apache.org/jira/browse/DERBY-3231
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.3.1.4
> Environment: Eclipse 3.2.2; java 1.5.0_11;
> Reporter: Peter Balon
> Assignee: Manish Khettry
> Priority: Critical
> Attachments: order_by_bug.diff.txt
>
>
> The result of the select is not sorted in "order by COUNT(*) DESC" or "order
> by COUNT(*) ASC"
> create table yy (a double, b double);
> insert into yy values (2, 4);
> insert into yy values (5, 7);
> insert into yy values (2, 3);
> insert into yy values (2, 3);
> insert into yy values (2, 3);
> insert into yy values (2, 3);
> insert into yy values (9, 7);
> select b, COUNT(*) AS "COUNT_OF", SUM(b) AS "sum b"
> from yy
> where a = 5 or a = 2
> group by b
> order by COUNT(*) asc
> -- same result as:
> select b, COUNT(*) AS "COUNT_OF", SUM(b) AS "sum b"
> from yy
> where a = 5 or a = 2
> group by b
> order by COUNT(*) desc
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