db-derby-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Mike Matrigali (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-532) Support deferrable constraints
Date Tue, 05 Nov 2013 18:17:19 GMT

    [ https://issues.apache.org/jira/browse/DERBY-532?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13814088#comment-13814088
] 

Mike Matrigali commented on DERBY-532:
--------------------------------------

i totally missed that this project was implementing yet another btree type, so sorry for late
review.  I am still
looking at detail, but wondering if you ever considered any solution that did not require
special case code
in the btree.  I would like to understand what would be the problem with implementing deferred
constraints
using existing "duplicate" btrees with no changes, and then do all deferred contraint checking
in the sql 
layer doing probes to ascertain constraint consistency using existing access interfaces (with
maybe something
more specialized if that allows for faster path).

I know you are following a path that the "unique" with duplicate code followed.  I have regretted
that approach
since it was implemented.  The project resulted in many bugs because of the complication involved
in twisting
the code to do something that it really did not want to do.  

> 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, deferredConstraints.html,
deferredConstraints.html, derby-532-import-1.diff, derby-532-import-1.status, derby-532-import-2.diff,
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, derby-532-unique-pk-1.diff, derby-532-unique-pk-1.status,
derby-532-unique-pk-2.diff, derby-532-xa-1.diff, derby-532-xa-2.diff
>
>
> 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.



--
This message was sent by Atlassian JIRA
(v6.1#6144)

Mime
View raw message