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From "A B (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-2526) Wrong query results due to column ordering in UNION view
Date Thu, 12 Apr 2007 23:33:15 GMT

    [ https://issues.apache.org/jira/browse/DERBY-2526?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12488534

A B commented on DERBY-2526:

Just a knee-jerk reaction to the DistinctTest failure: I wonder if the transitive closure
is leading to alteration or removal of predicates that break the conditions described here:


For example, there is some talk about how Derby will remove equijoin predicates as part of
transitive closure at the bottom of this page:


Maybe one of the equijoin predicates that is removed breaks the condition for DISTINCT elimination?

As I said, that's just knee-jerk feedback.  Apologies if it proves irrelevant...

> Wrong query results due to column ordering in UNION view
> --------------------------------------------------------
>                 Key: DERBY-2526
>                 URL: https://issues.apache.org/jira/browse/DERBY-2526
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions:,,,
>            Reporter: Bryan Pendleton
>         Assigned To: Bryan Pendleton
>         Attachments: badQuery.log, derby-2526.sql, DistinctTestNotes.txt, firstTryPatch.diff,
> I think both select statements in the attached repro script should return 1 row, but
in fact the first statement returns 1 row and the second returns zero rows.
> The only difference between the two statements is that the columns in the UNION view
are listed in a different order (bvw vs. bvw2).
> This seems like a bug to me; the order of the columns in the view definition shouldn't
matter, should it? 
> As Army noted on the derby-dev list, the fact that this reproduces with 10.0 means that
it is not caused by some of the 10.2 optimizer changes. Something else is going wrong.

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