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From "Daniel John Debrunner (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-3330) provide support for unique constraint over nullable columns
Date Thu, 28 Feb 2008 04:43:51 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3330?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12573151#action_12573151
] 

Daniel John Debrunner commented on DERBY-3330:
----------------------------------------------

Dibyendu wrote:

> one of the requirements is to allow multiple rows to be inserted where the index is unique
and all columns are null.

but not the only requirement :-)

In a unique constraint these key columns are allowed:

   Smith, NULL
   Smith, NULL
   Smith, NULL

A unique index (from existing CREATE INDEX) would only allow one row with Smith,NULL


 

> 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-3330v10.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, derbyall_report.txt,
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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