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From "Rick Hillegas (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-6004) Make it possible for table functions to declare that they return sorted results and make the optimizer exploit this information.
Date Tue, 04 Dec 2012 21:50:58 GMT

    [ https://issues.apache.org/jira/browse/DERBY-6004?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13510048#comment-13510048
] 

Rick Hillegas commented on DERBY-6004:
--------------------------------------

Hi Dag,

I went through exactly the same reasoning, starting out with ORDERED BY and ending up with
ORDER BY to avoid the extra keyword.

I think that collations introduce extra complexity but I would lump this case together with
the more general problem of an ordered table function which has a bug and returns a row order
which violates its contract. Here the table function declares that it returns rows in the
database's collation order, but in fact it doesn't. I see that as a bug in the table function.
I think the collation case would be handled by the solution to the general problem: have Derby
raise an exception when it detects an out-of-sequence row. 

Thanks,
-Rick
                
> Make it possible for table functions to declare that they return sorted results and make
the optimizer exploit this information.
> --------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-6004
>                 URL: https://issues.apache.org/jira/browse/DERBY-6004
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 10.10.0.0
>            Reporter: Rick Hillegas
>
> A derby-dev discussion has highlighted the need for table functions to return sorted
results which the optimizer can exploit. See http://old.nabble.com/Have-Derby-Network-Server-having-an-out-of-memory-%28PermGen%29-to34704415.html#a34706722

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