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From "Mark Holster (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-5151) Sequence without cache
Date Sat, 26 Mar 2011 09:10:05 GMT

    [ https://issues.apache.org/jira/browse/DERBY-5151?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13011586#comment-13011586
] 

Mark Holster commented on DERBY-5151:
-------------------------------------

Mike, 

I think I agree with you. After some readings I understand the standard describes a sequence
as a system to provide an unique number, with no guarantees for the order. For my usecase
I think I have to create a counter table with the right record locking etc to create the desired
functionality.

Furthermore, if it is still desired to create a patch that tunes the cache (by properties
or by sql) I'll try to create one. If not, I'm fine with closing the issue.

> Sequence without cache
> ----------------------
>
>                 Key: DERBY-5151
>                 URL: https://issues.apache.org/jira/browse/DERBY-5151
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>            Reporter: Mark Holster
>         Attachments: sequence-no-cache.patch
>
>
> Currently, a sequence in Derby always uses a pre allocating cache. I'm working on an
usecase which requires a number to increase with a fixed value. The usecase fails after a
restart because of the pre allocating cache.
> I've created a patch that adds the options CACHE | NO CACHE to the create sequence statement.
When no cache is provided, the pre allocating cache size will be set to 1, which results in
a "no cache sequence".
> I've followed the CYCLE | NO CYCLE code as much as possible. Tested it in my own app
and it seems to work fine.

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