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From "Mike Matrigali (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-3330) provide support for unique constraint over nullable columns
Date Mon, 18 Feb 2008 17:04:34 GMT

     [ https://issues.apache.org/jira/browse/DERBY-3330?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Mike Matrigali updated DERBY-3330:
----------------------------------


o although unlikely a legal state for a leaf page is to have a control row, but no other rows.
 It can
get this way if the deleted space background thread is able to reclaim the committed deleted
rows, but can't get table level lock to merge the empty leaf page.  Thus to handle this one
must be ready when scanning left and/or right to the next page looking for a row to need to
visit multiple
pages.

o with respect to isolation level.  What kind of locking will you be doing on the rows that
you are
checking left and right?  If you are locking those rows, how long will you hold those locks?
 The
search to the right is especially interesting as previously we would never have locked any
row
to the right of an insert.  With previous key locking used for isolation level implementation
the code
currently may or may not lock the left key, depending on isolation level.

> 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, FunctionalSpec_DERBY-3330-V2.html,
FunctionalSpec_DERBY-3330.html, UniqueConstraint_Implementation.html
>
>
> Allow unique constraint over nullable field. Right now derby support unique constraint
only over not null columns.

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