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From "Bryan Pendleton (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-2526) Wrong query results due to column ordering in UNION view
Date Tue, 10 Apr 2007 01:57:32 GMT

    [ https://issues.apache.org/jira/browse/DERBY-2526?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12487670

Bryan Pendleton commented on DERBY-2526:

Thanks much for the encouragement and kind words Army! They are much appreciated.

My observation for tonight is as follows:

*First*, we have the following:
  CursorNode.bindStatement calls
    SelectNode.bindResultColumns calls
      FromList.bindResultColumns calls
        JoinNode.bindResultColumns calls

Then, *later*, we have:
  CursorNode.optimizeStatement calls
    DMLStatementNode.optimizeStatement calls
      SelectNode.preprocess calls
        SelectNode.performTransitiveClosure calls

I'm wondering whether it would be possible to move the call
to SelectNode.performTransitiveClosure out of SelectNode.preprocess
and into the very start of SelectNode.bindResultColumns.

That is, do the transitive closure processing earlier, during
bind processing, rather than at the start of optimizing the statement.

I'll give this a try and see what my results are...

> 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, 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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