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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 Wed, 27 Feb 2008 22:13:51 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3330?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12573084#action_12573084
] 

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

I think the upgrade handling of IndexDescriptorImpl is too complex.

IndexDescriptorImpl uses a FormatableHashtable to store some of its state, the format of this
can handle additional or missing keys. Thus the additional boolean required by this change
can simply be added to the hash table, so the writeExternal has an additional:

     fh.putBoolean ("isUniqueWhenNotNull", isUniqueWhenNotNull);

and the readExternal can have:

   if (fh.containsKey("isUniqueWhenNotNull")
       isUniqueWhenNotNull = fh.getBoolean("isUniqueWhenNotNull");
   else
       isUniqueWhenNotNull = ?? ; // what ever is the correct value for old indexes.

Of course good to comment the real code with when & why these changes were made.

> 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, 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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