db-derby-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Bryan Pendleton (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-3330) provide support for unique constraint over keys that include one or more nullable columns.
Date Sun, 30 Mar 2008 14:53:25 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3330?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12583451#action_12583451
] 

Bryan Pendleton commented on DERBY-3330:
----------------------------------------

I came across this interesting discussion of the behavior of NULLs and UNIQUE constraints
in various database systems, and thought it might be interesting in the context of this
discussion: http://www.sqlite.org/nulls.html



> provide support for unique constraint over keys that include one or more nullable columns.
> ------------------------------------------------------------------------------------------
>
>                 Key: DERBY-3330
>                 URL: https://issues.apache.org/jira/browse/DERBY-3330
>             Project: Derby
>          Issue Type: New Feature
>          Components: SQL, Store
>    Affects Versions: 10.4.0.0
>         Environment: all
>            Reporter: Anurag Shekhar
>            Assignee: Anurag Shekhar
>         Attachments: BTreeController.diff, db2Compatibility-v2.diff, db2Compatibility.diff,
derby-3330-testcase.diff, derby-3330-UpgradeTests.diff, derby-3330.diff, derby-3330_followup_1.diff,
derby-3330_followup_1_modified.diff, derby-3330v10.diff, derby-3330v11.diff, derby-3330v12.diff,
derby-3330v13.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, sortercomments.diff, UniqueConstraint_Implementation.html,
UniqueConstraint_Implementation_V2.html, UniqueConstraint_Implementation_V3.html, UniqueConstraint_Implementation_V4.html
>
>
> Allow unique constraint over keys which include one or more nullable fields.  Prior to
this change Derby only supported unique constraints on keys that included no nullable columns.
 The new constraint will allow unlimited inserts of any key with one more null columns, but
will limit insert of keys with no null columns to 1 unique value per table.
> There is no change to existing or newly created unique indexes on null columns (as opposed
to unique constraints on null columns).  Also there is no change to existing or newly created
constraints on keys with no nullable columns.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


Mime
View raw message