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From Anurag shekhar <Anurag.Shek...@Sun.COM>
Subject Re: [jira] Commented: (DERBY-3330) provide support for unique constraint over nullable columns
Date Wed, 27 Feb 2008 20:50:36 GMT
Neighter the sql spec nor the derby manual promises this behavior 
(ordering of group by
clause without order by). So I don't think this is a deviation from the 
existing behavior.
anurag
Anurag shekhar wrote:
> Unique constraint on non nullable fields still act like a unique index 
> (because there is no null value) but internally they are backed by non 
> unique indexes with uniqueWhenNotNull attribute.
> anurag
>
> Mike Matrigali wrote:
>> I thought from functional spec and ongoing discussion that behavior 
>> of unique constraint on non-nullable columns would be unchanged.  So 
>> this
>> constraint should still be backed by a unique index.
>>
>> Anurag Shekhar (JIRA) wrote:
>>>     [ 
>>> https://issues.apache.org/jira/browse/DERBY-3330?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12573032#action_12573032

>>> ]
>>> Anurag Shekhar commented on DERBY-3330:
>>> ---------------------------------------
>>>
>>> dml019 test group by clause of unique constraint. When unique 
>>> constraint was backed by unique index, distinct scan  was used but 
>>> after making it non unique constraint this was not the case so the 
>>> results are not ordered.
>>> I have checked the test suite from nist web site and it mandates 
>>> only number of rows and not their sequence.
>>>> provide support for unique constraint over nullable columns
>>>> -----------------------------------------------------------
>>>>
>>>>                 Key: DERBY-3330
>>>>                 URL: https://issues.apache.org/jira/browse/DERBY-3330
>>>>             Project: Derby
>>>>          Issue Type: New Feature
>>>>          Components: Store
>>>>    Affects Versions: 10.4.0.0
>>>>         Environment: all
>>>>            Reporter: Anurag Shekhar
>>>>            Assignee: Anurag Shekhar
>>>>         Attachments: BTreeController.diff, 
>>>> derby-3330-testcase.diff, derby-3330.diff, derby-3330v2.diff, 
>>>> derby-3330v3.diff, derby-3330v4.diff, derby-3330v5.diff, 
>>>> derby-3330v6.diff, derby-3330v7.diff, derby-3330v8.diff, 
>>>> derby-3330v9.diff, FunctionalSpec_DERBY-3330-V2.html, 
>>>> FunctionalSpec_DERBY-3330.html, 
>>>> UniqueConstraint_Implementation.html, 
>>>> UniqueConstraint_Implementation_V2.html, 
>>>> UniqueConstraint_Implementation_V3.html
>>>>
>>>>
>>>> Allow unique constraint over nullable field. Right now derby 
>>>> support unique constraint only over not null columns.
>>>
>>
>


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