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From "Dag H. Wanvik (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-532) Support deferrable constraints
Date Tue, 06 Aug 2013 07:22:48 GMT

    [ https://issues.apache.org/jira/browse/DERBY-532?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13730469#comment-13730469
] 

Dag H. Wanvik commented on DERBY-532:
-------------------------------------

Just to be clear, the patch is of course not yet committed to the Apache repos. Regressions
ran ok.
Do people think its OK to build and commit this feature incrementally and just keep NOT IMPLEMENTED
messages until all is in place? I do not yet know how much work it will turn out to be in
the lower layers.

                
> Support deferrable constraints
> ------------------------------
>
>                 Key: DERBY-532
>                 URL: https://issues.apache.org/jira/browse/DERBY-532
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>            Reporter: Jörg von Frantzius
>              Labels: derby_triage10_11
>         Attachments: deferredConstraints.html, deferredConstraints.html, derby-532-syntax-binding-dict-1.diff,
derby-532-syntax-binding-dict-1.status
>
>
> In many situations it is desirable to have constraints checking taking place only at
transaction commit time, and not before. If e.g. there is a chain of foreign key constraints
between tables, insert statements have to be ordered to avoid constraint violations. If foreign
key references are circular, the DML has to be split into insert statements and subsequent
update statements by the user.
> In other words, with deferred constraints checking, life is much easier for the user.
Also it can create problems with softwares such as object-relational mapping tools that are
not prepared for statement ordering and thus depend on deferred constraints checking.

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