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https://issues.apache.org/jira/browse/DERBY-5151?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13098014#comment-13098014
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Rick Hillegas commented on DERBY-5151:
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Hi Kristian. Work on DERBY-4437 fixed a related problem: now we don't leak
identity/sequence values on normal exit. And work on that issue makes it
possible to set the length of the preallocated range to 1, which will stop
Derby from leaking identity/sequence values at the cost of reducing
scalability. However, if you want good scalability then you have to tolerate
leaking identity/sequence values on abnormal exit. So it seems to me that this
issue is still alive. Thanks-Rick
> Don't leak unused identity/sequence values on abnormal exit.
> ------------------------------------------------------------
>
> 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.
> RH: Note that part of this issue has been addressed by the work on
> DERBY-4437. Sequence values will NOT leak now if you perform an orderly
> shutdown of your database. However, values still leak if the VM exits before
> the database has been shutdown. I have changed this issue's title to indicate
> that the remaining work applies to both sequences and identity columns.
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