Yes. Daniel Reverri Developer Advocate Basho Technologies, Inc. d...@basho.com
On Thu, Dec 16, 2010 at 7:56 PM, Daniel Woo <daniel.y....@gmail.com> wrote: > Hi Daniel, > > So, the hashing algorithm is still consistent, but partitions (vnodes) are > re-distributed to nodes when new nodes are added, and the nodes gossip and > share the knowledge of the partition distribution, right? So the client can > query any of the nodes, if the node doesn't know where the partition located > it will query or gossip with adjacent nodes, right? > > Thanks, > Daniel > > > > On Fri, Dec 17, 2010 at 10:42 AM, Dan Reverri <d...@basho.com> wrote: > >> Hi Daniel, >> >> Clients do not specify the partition when making a request. A client can >> request any key from any node in the cluster and Riak will return the >> associated value. >> >> Thanks, >> Dan >> >> Daniel Reverri >> Developer Advocate >> Basho Technologies, Inc. >> d...@basho.com >> >> >> On Thu, Dec 16, 2010 at 6:01 PM, Daniel Woo <daniel.y....@gmail.com>wrote: >> >>> Hi Mark, >>> >>> Thanks for your explanation, so in this case the partitions would be >>> re-distributed >>> >>> *from* >>> >>> Node1: p1 ~ p16 >>> Node2: p17 ~ p32 >>> Node3: p33 ~ p48 >>> Node4: p49 ~ p64 >>> >>> *to * >>> Node1: p1 ~ p13 (remove 3 partitions) >>> Node2: p17 ~ p29 (remove 3 partitions) >>> Node3: p33 ~ p45 (remove 3 partitions) >>> Node4: p49 ~ p61 (remove 3 partitions) >>> Node5: p14, 15, 16, 30, 31, 32, 46, 47, 48, 62, 63, 64 (aprox 1/5 >>> partitions will be transferred to this new node) >>> >>> Since there is no centralized node in Riak, how do we know the partition >>> 32 is moved to node 5 from the client caller? Cassandra seems break half of >>> the adjacent node's data into the new node, that will be easy for the client >>> to search for the datum just around the node-circle clockwise, although it >>> causes unbalanced data distribution and you have to move them by command >>> lines. Riak seems to have this solved by moving partitions into new nodes >>> equally, that's very interesting, how do you guys make it? If the client >>> caller queries for partition 32 which was originally on node 2, how do the >>> client know it's on a new node now? >>> >>> Thanks, >>> Daniel >>> >>> >>> On Fri, Dec 17, 2010 at 6:56 AM, Mark Phillips <m...@basho.com> wrote: >>> >>>> Hey Daniel, >>>> >>>> [snip] >>>> >>>> > So, I guess Riak would have to re-hash the whole partitions into all >>>> the 5 >>>> > nodes, right? Is this done lazily when the node finds the requested >>>> data is >>>> > missing? >>>> > Or is there a way to handle this with consistent re-hashing so we can >>>> avoid >>>> > moving data around when new nodes added? >>>> > >>>> >>>> Riak won't rehash all the partitions in the ring when new nodes are >>>> added. When you go from 4 -> 5 nodes, for example, approx. 1/5 of the >>>> existing partitions are transferred to the new node. The other 4/5s of >>>> the partitions will remain unchanged. As far as moving data around >>>> when new nodes are added, this is impossible to avoid. Data needs to >>>> be handed off to be spread around the ring. >>>> >>>> Hope that helps. >>>> >>>> Mark >>>> >>> >>> >>> >>> -- >>> Thanks & Regards, >>> Daniel >>> >>> _______________________________________________ >>> riak-users mailing list >>> riak-users@lists.basho.com >>> http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com >>> >>> >> > > > -- > Thanks & Regards, > Daniel >
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