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From "Henning P. Schmiedehausen" <...@intermeta.de>
Subject Re: duplicate ID exception in cluster
Date Tue, 05 Dec 2006 22:18:23 GMT
"Will Glass-Husain" <wglass@forio.com> writes:


>I just set up a new 2 server cluster with two instances of Tomcat both
>reading/writing from a single database.  I'm using Torque 3.0, the
>default ID Broker and MySQL 5. (InnoDB)

Real cluster or just master/slave (or master/master with only one master
active at a time)? The latter is just replication, not a real cluster.

>My problem... Under heavy load, I notice that most write requests on
>one of the servers fails with a duplicate ID error.  Typically, each
>page request that fails does 10-20 insert statements.

>Any tips as to how I might make this cluster work with simultaneous writes?

a) in a master/master config, you can not write to both masters at the
   same time. End of story. I had a summer project where we tested
   exactly that *very* extensively. It does not work. No matter what you
   google on the internet or what mysql.com wants to tell you. You will
   get the described error sooner or later. If you want to have 
   master/master with failover, that is fine. Two active masters not.

b) you probably run into the AUTO_INCREMENT problem. Make sure that you
   have 5.0.20 at least. See http://dev.mysql.com/doc/refman/5.0/en/replication-features.html
   for some docs.

	Best regards

Henning P. Schmiedehausen  -- hps@intermeta.de | J2EE, Linux,
91054 Buckenhof, Germany   -- +49 9131 506540 | Apache person
Open Source Consulting, Development, Design | Velocity - Turbine guy

          "Save the cheerleader. Save the world."

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