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From "Rick Hillegas (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-532) Support deferrable constraints
Date Wed, 14 Aug 2013 15:43:50 GMT

    [ https://issues.apache.org/jira/browse/DERBY-532?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13739785#comment-13739785
] 

Rick Hillegas commented on DERBY-532:
-------------------------------------

Thanks for the patches, Dag. I was unable to apply them, maybe because the diff was produced
by git? When I try to apply the first patch via this command...

patch -p 0 -i $patchFile

...I get this error message:

can't find file to patch at input line 5
Perhaps you used the wrong -p or --strip option?
The text leading up to this was:
--------------------------
|diff --git a/java/engine/org/apache/derby/iapi/sql/dictionary/CheckConstraintDescriptor.java
b/java/engine/org/apache/derby/iapi/sql/dictionary/CheckConstraintDescriptor.java
|index 6378411..ceb2a99 100644
|--- a/java/engine/org/apache/derby/iapi/sql/dictionary/CheckConstraintDescriptor.java
|+++ b/java/engine/org/apache/derby/iapi/sql/dictionary/CheckConstraintDescriptor.java
--------------------------

Maybe I need to give the patch command another switch or argument?

Nevertheless, I did go through the patch files and have a couple, small comments:


---------

SYSCONSTRAINTSRowFactory:

o Could probably use a comment somewhere explaining the encoding
scheme for SYSCONSTRAINTS.STATE. Extra credit if the explanation is
something which would be easy to copy into the Reference Guide section
on this catalog. And/or update the functional spec accordingly.

---------

AlterConstraintConstantAction:

o Does this action need to invalidate statements?

Thanks,
-Rick

                
> 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
>
>
> 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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