It's worth adding that if you are using any kind of dynamic group (i.e. one that isn't specified statically at compile time) it's up to you to ensure you always return the same group for the same key! I'll add a big fat warning on this one!
On 17 May 2011, at 22:52, Pete Muir wrote: > Hi Erik > > I've evolved the api a small bit from the JIRA. The group generator now > behaves more like an interceptor than described in the jira (you can chain > them with the initial value being provided by the annotation). > > No, you don't need to know the group name to access the cache. The group is > simply used as a hint to Infinispan. > > > > On 17 May 2011, at 22:04, Erik Salter wrote: > >> Hi Manik, >> >> 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. >> >> 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) >> >> 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. >> >> Erik >> >> From: infinispan-dev-boun...@lists.jboss.org >> [mailto:infinispan-dev-boun...@lists.jboss.org] On Behalf Of Manik Surtani >> Sent: Tuesday, May 17, 2011 1:34 PM >> To: infinispan -Dev List >> Subject: [infinispan-dev] Grouping API (ISPN-312) WAS: Generated keys >> affected by rehash Was: https://issues.jboss.org/browse/ISPN-977 >> >> Erik, >> >> 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.) >> >> Have a look at the proposed API on https://issues.jboss.org/browse/ISPN-312 >> and let us know if it works for you. >> >> Cheers >> Manik >> >> On 13 May 2011, at 18:28, Erik Salter wrote: >> >> >> Hi Dan, >> >> 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. >> >> 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. >> >> Erik >> >> -----Original Message----- >> From: infinispan-dev-boun...@lists.jboss.org >> [mailto:infinispan-dev-boun...@lists.jboss.org] On Behalf Of Dan Berindei >> Sent: Friday, May 13, 2011 12:58 PM >> To: infinispan -Dev List >> Subject: Re: [infinispan-dev] Generated keys affected by rehash Was: >> https://issues.jboss.org/browse/ISPN-977 >> >> On Fri, May 13, 2011 at 6:38 PM, Erik Salter <esal...@bnivideo.com> wrote: >> >> Yes, collocation of all keys is a large concern of my application(s). >> >> 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. >> >> >> 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. >> >> >> 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. >> >> Cheers >> Dan >> >> >> >> Erik >> >> -----Original Message----- >> From: infinispan-dev-boun...@lists.jboss.org >> [mailto:infinispan-dev-boun...@lists.jboss.org] On Behalf Of Manik >> Surtani >> Sent: Friday, May 13, 2011 5:25 AM >> To: infinispan -Dev List >> Subject: [infinispan-dev] Generated keys affected by rehash Was: >> https://issues.jboss.org/browse/ISPN-977 >> >> >> On 11 May 2011, at 18:47, Erik Salter wrote: >> >> Wouldn't any rehash affect the locality of these generated keys, or am I >> missing something? >> >> 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? >> >> Cheers >> Manik >> -- >> Manik Surtani >> ma...@jboss.org >> twitter.com/maniksurtani >> >> Lead, Infinispan >> http://www.infinispan.org >> >> >> >> >> _______________________________________________ >> infinispan-dev mailing list >> infinispan-dev@lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/infinispan-dev >> >> The information contained in this message is legally privileged and >> confidential, and is intended for the individual or entity to whom it is >> addressed (or their designee). If this message is read by anyone other than >> the intended recipient, please be advised that distribution of this message, >> in any form, is strictly prohibited. If you have received this message in >> error, please notify the sender immediately and delete or destroy all copies >> of this message. >> >> _______________________________________________ >> infinispan-dev mailing list >> infinispan-dev@lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/infinispan-dev >> >> >> _______________________________________________ >> infinispan-dev mailing list >> infinispan-dev@lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/infinispan-dev >> >> The information contained in this message is legally privileged and >> confidential, and is intended for the individual or entity to whom it is >> addressed (or their designee). If this message is read by anyone other than >> the intended recipient, please be advised that distribution of this message, >> in any form, is strictly prohibited. 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