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From "ASF subversion and git services (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-532) Support deferrable constraints
Date Tue, 27 Aug 2013 14:05:52 GMT

    [ https://issues.apache.org/jira/browse/DERBY-532?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13751279#comment-13751279
] 

ASF subversion and git services commented on DERBY-532:
-------------------------------------------------------

Commit 1517823 from [~dagw] in branch 'code/trunk'
[ https://svn.apache.org/r1517823 ]

DERBY-532 Support deferrable constraints

Patch derby-532-syntax-binding-dict-all-1. This patch wires in the syntax
for deferred constraints (aka "constraint characteristics"). It also
does

- binding checks for CREATE TABLE constraints and SET constraints
  statement (new). Binding is still missing for ALTER TABLE
  constraints clauses.

- temporarily throws not yet implemented (0A000.S) for all usage
  *except* when characteristics coincide with the current (and future)
  Derby defaults, i.e. NOT DEFERRABLE [INITIALLY IMMEDIATE] ENFORCED

- checks inconsistencies in characteristics (illegal combinations), cf.
  42X97 "Conflicting constraint characteristics for constraint"

- implements implied DEFERRABLE of (only) INITIALLY DEFERRED is
  specified.

- if the property "derby.constraintsTesting" is set, persists
  characteristics to dictionary by overloading the existing STATE
  character according to specification. This property will go away
  once the feature set is implemented, only implemented not to be able
  to test dictionary persistence

- throws 42XAK "Constraint characteristics not allowed for NOT NULL."
  for NOT NULL characteristics since this constraint type is not
  explicitly implemented as a constraint in Derby (yet, at least)

- adds a new test, ConstraintCharacteristicsTest to test the above and
  wires it into the lang suite.

(part 2):
- Elaborates ALTER TABLE ALTER TABLE, correcting syntax, adding name
  binding and updating dictionary (subject to the property
  derby.constraintsTesting) in a new AlterConstraintConstantAction
  class.

- Built out tests in ConstraintCharacteristicsTest to systematically
  check all possible characteristics combinations in all cases, and
  adding tests for ALTER TABLE ALTER TABLE, including dictionary
  updates.
                
> 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
>
>
> 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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