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From "Mamta A. Satoor (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-4331) Join returns results in wrong order
Date Wed, 05 Aug 2009 19:38:17 GMT

    [ https://issues.apache.org/jira/browse/DERBY-4331?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12739698#action_12739698
] 

Mamta A. Satoor commented on DERBY-4331:
----------------------------------------

Mike and I have been talking about different possibilities for DERBY-4331/DERBY-3926 given
the time critical nature of it. We decided that we will investigate the fix for DERBY-3926
to see what can be backed out and at the same time debug the reason beind DERBY-4331 failure.
I will write the information I have collected over last couple days on the reason behind the
bug DERBY-4331 and apossible fix for it but first would like to comment on Mike's proposal
about backing out some of DERBY-3926 changes

I agree with the partial backout of DERBY-3926. The code proposed for backout was written
to cover additional queries so that we can avoid sorting for them if possible but from what
I recall, it was not needed for fixing DERBY-3926. So it should be safe to backout part of
the change w/o impacting any queries negatively. It will be good to do full tests before we
commit those changes though.

> Join returns results in wrong order
> -----------------------------------
>
>                 Key: DERBY-4331
>                 URL: https://issues.apache.org/jira/browse/DERBY-4331
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 10.5.2.0, 10.6.0.0
>            Reporter: Knut Anders Hatlen
>            Assignee: Mike Matrigali
>         Attachments: createDBsimpler.txt, createDBsimplerVer2.txt, derby4331_do_not_commit.diff,
notorderby4331.zip, orderby4331.zip, repro.sql, repro2.sql, repro2_qryplan.txt
>
>
> In Derby 10.5.2.0, the query below started returning results in wrong order (note the
ORDER BY clause). Derby 10.5.1.1 gives the expected ordering.
> ij> SELECT CS.ID
> FROM
>     CHANGESETS CS, FILECHANGES FC, REPOSITORIES R, FILES F, AUTHORS A
> WHERE
>     R.PATH = '/var/tmp/source5923202038296723704opengrok/mercurial' AND F.REPOSITORY
= R.ID AND A.REPOSITORY = R.ID AND
>     CS.REPOSITORY = R.ID AND CS.ID = FC.CHANGESET AND F.ID = FC.FILE AND
>     A.ID = CS.AUTHOR AND
>     EXISTS (
>         SELECT 1
>         FROM FILES F2
>         WHERE
>             F2.ID = FC.FILE AND F2.REPOSITORY = R.ID AND
>             F2.PATH LIKE '/%' ESCAPE '#')
> ORDER BY CS.ID DESC;
> ID         
> -----------
> 1          
> 2          
> 3          
> 2          
> 2          
> 3          
> 6 rows selected

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