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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 23:46:15 GMT

    [ https://issues.apache.org/jira/browse/DERBY-2526?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12488537
] 

A B commented on DERBY-2526:
----------------------------

> I thought that the transitive closure processing was only looking at join conditions,
> not at simple restriction conditions ("tt2.c2 = 3"), but perhaps I was wrong.

There are two types of transitive closure:

  http://db.apache.org/derby/docs/dev/tuning/ctuntransform37032.html

The first is join conditions, as you've noticed.  The second is "search conditions" and does
indeed take into account predicates like "tt2.c2 = 3", so maybe this is why you are seeing
the different plans?

> 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: 10.0.2.1, 10.1.3.1, 10.2.2.0, 10.3.0.0
>            Reporter: Bryan Pendleton
>         Assigned To: Bryan Pendleton
>         Attachments: badQuery.log, derby-2526.sql, DistinctTestNotes.txt, firstTryPatch.diff,
goodQuery.log
>
>
> 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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