Le 02/09/2014 12:02, Adrian Crum a écrit :
Moving this discussion to the dev mailing list since the Jira issue is closed.
Jacques,
The description of the current design can be found here:
http://ofbiz.apache.org/docs/entity.html
where it says:
"For unique primary key generation we use an original pattern we like to call the "Ethernet Key Generation" pattern because it uses a collision
detection mechanism to insure that multiple servers can use a single database to get banks of unique keys in a database independent way."
So, the document is making an analogy - it is saying the design is LIKE Ethernet collision detection. The term "CSMA/CD" is an Ethernet term, not a
software design term.
I don't want to go on and on on this, I was just saying it's a pattern "like" CSMA/CD, to quickly grab the idea. BTW, as pointed Jacopo we should
update that document if we keep as current...
Note that the previous implementation of the pattern was faulty, hence my hasty
introduction of SELECT FOR UPDATE (in the middle of a project).
Jacques
Adrian Crum
Sandglass Software
www.sandglass-software.com
On 9/2/2014 10:10 AM, Jacques Le Roux (JIRA) wrote:
[
https://issues.apache.org/jira/browse/OFBIZ-2353?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14118052#comment-14118052
]
Jacques Le Roux commented on OFBIZ-2353:
----------------------------------------
Thanks for your explanation Adrian, so the known pattern in code litterature is
the CSMA/CD.
About performance, we should remember that the size of the bank is an important
parameter here.
If performance is a crucial concern, people might look at using solution like
CREATE SEQUENCE... Of course not in OFBiz OOTB...
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, Trunk
Reporter: Philippe Mouawad
Assignee: Jacopo Cappellato
Priority: Critical
Fix For: Release Branch 10.04, Upcoming Branch
Attachments: OFBIZ-2353 SELECT FOR UPDATE solution.patch, OFBIZ-2353 SELECT FOR UPDATE solution.patch, OFBIZ-2353-AC.patch,
OFBIZ-2353-AC.patch
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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