[jboss-jira] [JBoss JIRA] Commented: (JBAS-5231) cluster-safe configuration for HILOSEQUENCES is not enabled in the "all" server conf

Tue Mar 18 08:33:50 EDT 2008

    [ http://jira.jboss.com/jira/browse/JBAS-5231?page=comments#action_12403355 ] 

Alexey Loubyansky commented on JBAS-5231:
-----------------------------------------

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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