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http://jira.jboss.com/jira/browse/JBAS-5231?page=comments#action_12403355 ]
Alexey Loubyansky commented on JBAS-5231:
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After looking into this, I am not sure whether we should fix it as suggested.
First of all, it's backed by Hypersonic.
Any user that is going to use the service in production will most probably change it and
this would imply changing the configuration of the service. So, I assume the service as-is
in the cluster would be used for testing/trying.
A fix I would go with is using SelectHiSql by default in all the configurations (since
it's safer, shouldn't kill performance and finally it's still assumed to be
used for testing) and update the comment with an optimization hint to comment it out if
there is no other process using the same table. But then we would have to remove the FOR
UPDATE part since the Hypersonic version we are currently using in trunk doesn't
support the syntax. W/o FOR UPDATE it will actually work but there could be unsuccessful
UPDATEs in the background (which won't affect users).
But now looking at the impl with SelectHiSql commented, I don't see why that would be
not cluster safe. The synch of the current Hi value with the value from the db is based on
successful execution of the UPDATE anyway. It means there would just be even more failed
UPDATEs than in case w/o FOR UPDATE but that still should work.
So, maybe all we should fix is the docs.
cluster-safe configuration for HILOSEQUENCES is not enabled in the
"all" server conf
-------------------------------------------------------------------------------------
Key: JBAS-5231
URL:
http://jira.jboss.com/jira/browse/JBAS-5231
Project: JBoss Application Server
Issue Type: Bug
Security Level: Public(Everyone can see)
Components: Clustering
Affects Versions: JBossAS-5.0.0.Beta4
Reporter: Luc Texier
Assigned To: Alexey Loubyansky
\jboss-5.0.0.Beta4\server\all\deploy\uuid-key-generator.sar\META-INF
In the EAP "production" configuration, the following attribute is enabled by
default. Not in the "all"configuration which is clustered by definition
<!-- Uncomment to make it cluster-safe: Select current Hi value query (FOR UPDATE
is recommended) -->
<attribute name="SelectHiSql">
select HIGHVALUES from HILOSEQUENCES where SEQUENCENAME='general' FOR
UPDATE
</attribute>
some more information
http://wiki.jboss.org/wiki/Wiki.jsp?page=CMPHiLoKeyGenerator
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