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https://issues.apache.org/jira/browse/OFBIZ-2353?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13037646#comment-13037646 ]
Jacques Le Roux edited comment on OFBIZ-2353 at 5/31/11 9:06 AM:
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Philippe,
Yes thanks, but of course I don't intend to keep maxTries at 100 (we have other priorities at the moment). I was considering the SELECT FOR UPDATE solution because, as you said, it allows a totally DBMS independent solution. So an alternative in clustered environment for OFBiz OOTB. And I don't digg it in yet, but it sounds like it could be used w/out much changes, ie replace
{
sql = "SELECT " + SequenceUtil.this.idColName + " FROM " + SequenceUtil.this.tableName + " WHERE " + SequenceUtil.this.nameColName + "='" + this.seqName + "'";
}
by
{
sql = "SELECT " + SequenceUtil.this.idColName + " FROM " + SequenceUtil.this.tableName + " WHERE " + SequenceUtil.this.nameColName + "='" + this.seqName + "'" + " FOR UPDATE";
}
But once more I guess a CREATE SEQUENCE solution would give better performance (no contention, optimized DBMS internal mechanism). So I plan (have to look into details next week) to keep maxTries to 5 (should not be needed anymore, but I will make as less changes as possible in this next quick iteration) and use SELECT FOR UPDATE there, before implementing a complete solution based on CREATE SEQUENCE for the project (we use Postgres).
was (Author: jacques.le.roux):
Philippe,
Yes thanks, but of course I don't intend to keep maxTries at 100 (we have other priorities at the moment). I was considering the SELECT FOR UPDATE solution because, as you said, it allows a totally DBMS independent solution. So an alternative in clustered environment for OFBiz OOTB. And I don't digg it in yet, but it sounds like it could be used w/out much changes, ie replace
{
sql = "SELECT " + SequenceUtil.this.idColName + " FROM " + SequenceUtil.this.tableName + " WHERE " + SequenceUtil.this.nameColName + "='" + this.seqName + "'";
}
by
{
sql = "SELECT FOR UPDATE" + SequenceUtil.this.idColName + " FROM " + SequenceUtil.this.tableName + " WHERE " + SequenceUtil.this.nameColName + "='" + this.seqName + "'";
}
But once more I guess a CREATE SEQUENCE solution would give better performance (no contention, optimized DBMS internal mechanism). So I plan (have to look into details next week) to keep maxTries to 5 (should not be needed anymore, but I will make as less changes as possible in this next quick iteration) and use SELECT FOR UPDATE there, before implementing a complete solution based on CREATE SEQUENCE for the project (we use Postgres).
> SequenceUtil may generate duplicate IDs in Load Balancing mode
> ---------------------------------------------------------------
>
> Key: OFBIZ-2353
> URL:
https://issues.apache.org/jira/browse/OFBIZ-2353> Project: OFBiz
> Issue Type: Bug
> Components: framework
> Affects Versions: Release Branch 4.0, Release Branch 09.04, SVN trunk
> Reporter: Philippe Mouawad
> Assignee: Adam Heath
> Priority: Critical
>
> If Ofbiz is deploy on 2 servers in Load Balancing Mode
> SequenceUtil will generate duplicate IDs because synchronization is done at JVM level instead of doing it in DB.
> A good replacement implementation would be:
> org.hibernate.id.enhanced.TableGenerator
> But it would involve a dependency on Hibernate
> Philippe
> www.ubik-ingenierie.com
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