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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hi Manik,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I think we are in agreement that playing with hash codes was only a temporary measure. In my case, having < 200 entries with the same hash code was worth it
for knowing that I could handle transactions locally and reap the benefits of increased throughput. So I can now replace the hash code with @Group. Cool.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The group generator interface looks interesting, since it closest reflects my situation. I now have requirements where an immutable key class will need to
be saved within the same transaction as the scenario above (obviously, hashing to the same node is a plus) <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">One thing isn’t clear from the JIRA. If I wanted to get Employee “SteveVai” from the cache, do I need to know the group context is “com.ibanez.SteveVai”?
My calling application only knows the key value, not the value with the key context.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Erik<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> infinispan-dev-bounces@lists.jboss.org [mailto:infinispan-dev-bounces@lists.jboss.org]
<b>On Behalf Of </b>Manik Surtani<br>
<b>Sent:</b> Tuesday, May 17, 2011 1:34 PM<br>
<b>To:</b> infinispan -Dev List<br>
<b>Subject:</b> [infinispan-dev] Grouping API (ISPN-312) WAS: Generated keys affected by rehash Was: https://issues.jboss.org/browse/ISPN-977<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Erik,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Dan is correct that playing with hash codes is not the correct solution. ISPN-312 is the correct approach. Pete has been working on a first-cut of this and it should make 5.0.0.CR3. (Understood that release candidates aren't the place
to add new features, but we're adding it as a "preview", just to get feedback on the API and impl.)<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Have a look at the proposed API on <a href="https://issues.jboss.org/browse/ISPN-312">https://issues.jboss.org/browse/ISPN-312</a> and let us know if it works for you.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Cheers<o:p></o:p></p>
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<p class="MsoNormal">Manik<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">On 13 May 2011, at 18:28, Erik Salter wrote:<o:p></o:p></p>
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<p class="MsoNormal"><br>
<br>
<o:p></o:p></p>
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<p class="MsoNormal">Hi Dan,<br>
<br>
I don't necessarily care about which server it's on, as long as the keys for my set of caches all remain collocated. I understand they will all end up in the same bucket, but for one hash code, that's at most 200 keys. I must acquire a lock for a subset of
them during a transaction -- so I make liberal use of the "eagerLockSingleNode" option and redirecting my calling application to execute a transaction on the local node. Acquiring cluster-wide locks is an absolute throughput killer.<br>
<br>
I took a look at the KeyAffinityService a while ago (when it came out) and quickly realized it would not be suitable for my purposes. I was wondering if ISPN-977 would allow me to use it. But you're right. What I ultimately want is ISPN-312.<br>
<br>
Erik<br>
<br>
-----Original Message-----<br>
From: <a href="mailto:infinispan-dev-bounces@lists.jboss.org">infinispan-dev-bounces@lists.jboss.org</a> [mailto:infinispan-dev-bounces@lists.jboss.org] On Behalf Of Dan Berindei<br>
Sent: Friday, May 13, 2011 12:58 PM<br>
To: infinispan -Dev List<br>
Subject: Re: [infinispan-dev] Generated keys affected by rehash Was: <a href="https://issues.jboss.org/browse/ISPN-977">
https://issues.jboss.org/browse/ISPN-977</a><br>
<br>
On Fri, May 13, 2011 at 6:38 PM, Erik Salter <<a href="mailto:esalter@bnivideo.com">esalter@bnivideo.com</a>> wrote:<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal">Yes, collocation of all keys is a large concern of my application(s).<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Currently, I can handle keys I'm in control of (like database-generated keys), where I can play around with the hash code. What I would love to do is collocate that data with keys I can't control (like UUIDs) so that all cache operations
can be done in the same transaction on the data owner's node.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><br>
By playing around with the hash code do you mean you set the hashcode for all the keys you want on a certain server to the same value? I imagine that would degrade performance quite a bit, because we have HashMaps everywhere and your keys will always end up
in the same hash bucket.<br>
<br>
<br>
ISPN-312 seems to me like a much better fit for your use case than the KeyAffinityService. Even if you added a listener to change your keys when the topology changes, that would mean on a rehash the keys could get moved to the new server and then back to the
old server, whereas with ISPN-312 they will either all stay on the old node or they will all move to the new node.<br>
<br>
Cheers<br>
Dan<br>
<br>
<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal">Erik<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">-----Original Message-----<o:p></o:p></p>
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<p class="MsoNormal">From: <a href="mailto:infinispan-dev-bounces@lists.jboss.org">
infinispan-dev-bounces@lists.jboss.org</a><o:p></o:p></p>
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<p class="MsoNormal">[mailto:infinispan-dev-bounces@lists.jboss.org] On Behalf Of Manik<o:p></o:p></p>
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<p class="MsoNormal">Surtani<o:p></o:p></p>
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<p class="MsoNormal">Sent: Friday, May 13, 2011 5:25 AM<o:p></o:p></p>
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<p class="MsoNormal">To: infinispan -Dev List<o:p></o:p></p>
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<p class="MsoNormal">Subject: [infinispan-dev] Generated keys affected by rehash Was:<o:p></o:p></p>
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<p class="MsoNormal"><a href="https://issues.jboss.org/browse/ISPN-977">https://issues.jboss.org/browse/ISPN-977</a><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On 11 May 2011, at 18:47, Erik Salter wrote:<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Wouldn't any rehash affect the locality of these generated keys, or am I missing something?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">It would. And hence ISPN-977, to address that. Or is your concern keys already generated before the rehash? The latter would certainly be a problem. Perhaps, if this was important to the application, on detecting a change in topology,
re-generate keys and move data around? For other apps, move the "session" to the appropriate node?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Cheers<o:p></o:p></p>
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<p class="MsoNormal">Manik<o:p></o:p></p>
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<p class="MsoNormal">--<o:p></o:p></p>
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<p class="MsoNormal">Manik Surtani<o:p></o:p></p>
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<p class="MsoNormal"><a href="mailto:manik@jboss.org">manik@jboss.org</a><o:p></o:p></p>
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<p class="MsoNormal"><a href="http://twitter.com/maniksurtani">twitter.com/maniksurtani</a><o:p></o:p></p>
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