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 <esalter(a)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-bounces(a)lists.jboss.org
[mailto:infinispan-dev-bounces@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
manik(a)jboss.org
twitter.com/maniksurtani
Lead, Infinispan
http://www.infinispan.org
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