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https://issues.apache.org/jira/browse/DERBY-532?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13754978#comment-13754978
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ASF subversion and git services commented on DERBY-532:
-------------------------------------------------------

Commit 1519045 from [~dagw] in branch 'code/trunk'
[ https://svn.apache.org/r1519045 ]

DERBY-532: Support deferrable constraints

Patch derby-532-testAlterConstraintInvalidation.

Adds a fixture to test that prepared statement is invalidated when a
table its depends on undergoes an ALTER TABLE ALTER CONSTRAINT
statement. As it turns out, this is already handled by the common
machinery for ALTER TABLE.
                
> 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
>            Assignee: Dag H. Wanvik
>              Labels: derby_triage10_11
>         Attachments: deferredConstraints.html, deferredConstraints.html, 
> derby-532-syntax-binding-dict-1.diff, derby-532-syntax-binding-dict-1.status, 
> derby-532-syntax-binding-dict-2.diff, derby-532-syntax-binding-dict-2.status, 
> derby-532-syntax-binding-dict-all-1.diff, 
> derby-532-testAlterConstraintInvalidation.diff, 
> derby-532-testAlterConstraintInvalidation.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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