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https://issues.apache.org/jira/browse/DERBY-681?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12480437
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A B commented on DERBY-681:
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Actually, it turns out that just switching to "visibleSize()" does *not* solve
the problem. I made that change to a clean codeline and the error still
occurs. When I printed out the values of "size()" and "visibleSize()", they
*both* showed "2".
I don't know if it's relevant, but if you add a group by clause to the query,
it runs fine:
select distinct vc, x from t1 as myt1
where d <= (select max(myt1.d) from t1 as myt2
where myt1.vc = myt2.vc and myt1.d <= myt2.d
group by d
having count(distinct d) <= 3);
Manish, would you be willing to look into this a bit more?
> Eliminate the parser's rewriting of the abstract syntax tree for queries with
> GROUP BY and/or HAVING clauses
> ------------------------------------------------------------------------------------------------------------
>
> Key: DERBY-681
> URL: https://issues.apache.org/jira/browse/DERBY-681
> Project: Derby
> Issue Type: Improvement
> Components: SQL
> Reporter: Rick Hillegas
> Assigned To: Manish Khettry
> Attachments: 681.patch.txt, 681.patch2.txt, 681.patch3.txt, notes.txt
>
>
> If a query contains a GROUP BY or HAVING clause, the parser rewrites the
> abstract syntax tree, putting aggregates into a subselect and treating the
> HAVING clause as the WHERE clause of a fabricated outer select from the
> subquery. This allows the compiler to re-use some machinery since the HAVING
> clause operates on the grouped result the way that the WHERE clause operates
> on the from list. Unfortunately, this rewriting creates an explosion of
> special cases in the compiler after parsing is done. The rewriting is not
> systematically handled later on in the compiler. This gives rise to defects
> like bug 280. We need to eliminate this special rewriting and handle the
> HAVING clause in a straightforward way. This is not a small bugfix but is a
> medium sized project.
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