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https://issues.apache.org/jira/browse/DERBY-2526?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12488537
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A B commented on DERBY-2526:
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> 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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