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From "Bryan Pendleton (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-2887) NULLS FIRST / LAST for ORDER BY
Date Sat, 18 Aug 2007 20:05:30 GMT

    [ https://issues.apache.org/jira/browse/DERBY-2887?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12520889
] 

Bryan Pendleton commented on DERBY-2887:
----------------------------------------

The implementation is intended to use indexes in the cases where indexes are currently used.

That is, in the index, NULL values are *always* sorted high, so if the NULL FIRST/LAST setting
is such that the index can be used to satisfy the ORDER BY, then it will be used. Otherwise,
a sort will be required.

It would be great if you can verify this independently. I added a test to the regression suite,
but
more tests are always helpful.


> NULLS FIRST / LAST for ORDER BY
> -------------------------------
>
>                 Key: DERBY-2887
>                 URL: https://issues.apache.org/jira/browse/DERBY-2887
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>            Reporter: Christian d'Heureuse
>            Assignee: Bryan Pendleton
>            Priority: Minor
>             Fix For: 10.4.0.0
>
>         Attachments: nullOrderingPatch.diff, prototypeCodeNoTests.diff, prototypeCodeNoTests_v2.diff,
prototypeCodeNoTests_v3.diff
>
>
> I suggest to implement the "null ordering" option for the "ORDER BY" clause:
> According to the SQL standard, 10.10 <sort specification list>:
>  <null ordering> ::=
>     NULLS FIRST
>     | NULLS LAST

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