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From "ASF subversion and git services (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-6903) ALTER TABLE ALTER COLUMN resets CYCLE option of IDENTITY column
Date Thu, 01 Jun 2017 22:03:05 GMT

    [ https://issues.apache.org/jira/browse/DERBY-6903?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16033787#comment-16033787
] 

ASF subversion and git services commented on DERBY-6903:
--------------------------------------------------------

Commit 1797283 from [~bryanpendleton] in branch 'code/trunk'
[ https://svn.apache.org/r1797283 ]

DERBY-6903: ALTER TABLE ALTER COLUMN resets CYCLE option
DERBY-6904: Enhance ALTER TABLE to allow CYCLE option to be changed
DERBY-6905: Enhance SYS.SYSCOLUMNS to report the CYCLE value
DERBY-6906: Allow a GENERATED column to explicitly specify NO CYCLE

This patch was contributed by Harshvardhan Gupta (harshvardhan145 at gmail dot com)

The patch adds the CYCLE property as a fundamental property associated
with a column similar to current increment value, current increment step etc.

 *  SYS.SYSCOLUMNS extended to hold the cycle value of identity column.
 *  Extended the grammar to accept "cycle","no cycle" in alter clause
    and changed the underlying column descriptor and sequencing objects.
 *  ALTER clause not involving cycle option (i.e increment and restart)
    won't affect the cycle option.

The code flow for the upgrade handling was modelled after Derby-534
for introducing a new in column SYSTRIGGERS. There are new behaviors
for SYSCOLUMNS in both soft- and hard-upgrade scenarios.

> ALTER TABLE ALTER COLUMN resets CYCLE option of IDENTITY column
> ---------------------------------------------------------------
>
>                 Key: DERBY-6903
>                 URL: https://issues.apache.org/jira/browse/DERBY-6903
>             Project: Derby
>          Issue Type: Sub-task
>          Components: SQL
>    Affects Versions: 10.13.1.0
>            Reporter: Bryan Pendleton
>            Assignee: Harshvardhan Gupta
>            Priority: Minor
>
> Using ALTER TABLE with the SET INCREMENT BY or SET RESTART WITH
> options to make a change to a GENERATED ... BY IDENTITY column resets the CYCLE option
of that column to "off".
> Some test cases demonstrating this behavior were added as part of
> the DERBY-6852 change revision 1756287
> The problem occurs when the ALTER TABLE code drops and recreates
> the underlying SEQUENCE object, and does not preserve the CYCLE
> option of the underlying SEQUENCE object.
> I believe the correct behavior would be for the ALTER TABLE code
> to read the current CYCLE option of the underlying SEQUENCE object
> first, and then create the new SEQUENCE object with the same value
> for the CYCLE option.



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