[
https://issues.apache.org/jira/browse/DERBY-5493?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13252725#comment-13252725
]
Rick Hillegas commented on DERBY-5493:
--------------------------------------
I have run a quick concurrency test against the patch, using the test
introduced on derby-4565:
java org.apache.derbyTesting.perf.clients.Runner \
-driver org.apache.derby.jdbc.EmbeddedDriver \
-init \
-load seq_gen \
-load_opts
debugging=0,numberOfGenerators=1,tablesPerGenerator=0,insertsPerTransaction=100
\
-gen b2b \
-threads 10 \
On my dual-core Mac I'm getting slightly better numbers (average of 291
tx/seconds) than I recorded for this test case on derby-4565. I don't think the
improvement is due to this patch, it is more likely due to the fact that I have
a faster machine this time around. However, it encourages me to think that the
patch has not harmed the concurrency of sequence generators. I'm looking for a
beefier machine with more processors now.
> Same value returned by successive calls to a sequence generator.
> ----------------------------------------------------------------
>
> Key: DERBY-5493
> URL: https://issues.apache.org/jira/browse/DERBY-5493
> 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
> Assignee: Rick Hillegas
> Labels: derby_triage10_9
> Attachments: derby-5493-01-aa-correctnessPlusPeekerPlusTest.diff,
> derby-5493-01-ad-simplerApproach.diff,
> derby-5493-01-ae-simplerApproachWithCrashJUnitTest.diff
>
>
> The following script shows the same value being returned from a sequence
> generator by two successive NEXT VALUE FOR calls. Thanks to Knut for finding
> this:
> connect 'jdbc:derby:memory:db;create=true';
> create table t (x int);
> create sequence s;
> autocommit off;
> select count(*) from sys.syssequences with rs;
> values next value for s;
> drop table t;
> rollback;
> -- same value as previous call
> values next value for s;
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
