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https://issues.apache.org/jira/browse/DERBY-5494?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13251895#comment-13251895
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Mike Matrigali commented on DERBY-5494:
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i am looking at the latest test case posted in comments. Looking at log traces
is seems like update of catalog row does get done in a nested transaction, and
commit record is written to stream, but does not look like a force of the log
is happening at that point. Not sure why not, yet. For some internal/nested
transactions this behavior is ok as rather get the performance of a nosync
commit and we don't really care as long as either all or none of the
transaction gets done. The is the case with btree splits. I think it also
makes sense for identity columns as the nested transaction only is important
once some other transaction that uses one of the value commits, which in turn
will force this transaction.
I don't think sequences should be using this optimization and thought that only
would happen if they called commitNoSync() which I did not see in the code.
> Same value returned by successive calls to a sequence generator flanking an
> unorderly shutdown.
> -----------------------------------------------------------------------------------------------
>
> Key: DERBY-5494
> URL: https://issues.apache.org/jira/browse/DERBY-5494
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.6.1.0, 10.6.2.1, 10.7.1.1, 10.8.1.2, 10.8.2.2,
> 10.9.0.0
> Reporter: Rick Hillegas
> Labels: derby_triage10_9
>
> The following sequence of steps causes a sequence generator to return the
> same value on successive NEXT VALUE FOR calls.
> 1) Bring up ij and issue the following commands:
> connect 'jdbc:derby:db;create=true';
> create sequence s;
> values next value for s;
> 2) Control-c out of ij so that the engine comes down hard without an orderly
> shutdown.
> 3) Now bring up ij again and issue the following commands:
> connect 'jdbc:derby:db';
> values next value for s;
> Thanks to Knut for finding this one.
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