To the degree that this suggests that there is a "master" node for each range, IMO it is a "bug" in the paper. (There are several of these.) Certainly there are no master nodes in Cassandra.
On Fri, Sep 3, 2010 at 12:02 AM, Ying Tang <ivytang0...@gmail.com> wrote: > In dynamo's paper ,it says: > Each key, k, is assigned to a coordinator node . > The coordinator is in charge of the replication of the data items that fall > within its range. > On Fri, Sep 3, 2010 at 2:56 PM, Benjamin Black <b...@b3k.us> wrote: >> >> On Thu, Sep 2, 2010 at 8:19 PM, Ying Tang <ivytang0...@gmail.com> wrote: >> > Recently , i read the paper about Cassandra again . >> > And now i have some concepts about the reading and writing . >> > We all know Cassandra uses NWR , >> > When read : >> > the request ---> a random node in Cassandra .This node acts as a proxy >> > ,and >> > it routes the request. >> > Here , >> > 1. the proxy node route this request to this key's coordinator , the >> > coordinator then routes request to other N-1 nodes OR the proxy >> > routes >> > the read request to N nodes ? >> >> The coordinator node is the proxy node. >> >> > 2. If it is the former situation , the read repair occurs on the key's >> > coordinator ? >> > If it is the latter , the read repair occurs on the proxy node ? >> >> Depends on the CL requested. QUORUM and ALL cause the RR to be >> performed by the coordinator. ANY and ONE cause RR to be delegated to >> one of the replicas for the key. >> >> > When write : >> > the request ---> a random node in Cassandra .This node acts as a proxy >> > ,and >> > it routes the request. >> > Here , >> > 3. the proxy node route this request to this key's coordinator , the >> > coordinator then routes request to other N-1 nodes OR the proxy >> > routes >> > the request to N nodes ? >> > >> >> For writes, the coordinator sends the writes directly to the replicas >> regardless of CL (rather than delegating for weakly consistent CLs). >> >> > 4. The N isn't the data's copy numbers , it's just a range . In this N >> > range , there must be W copies .So W is the copy numbers. >> > So in this N range , R+W>N can guarantee the data's validity. Right? >> > >> >> Sorry, I can't even parse this. >> >> >> b > > > > -- > Best regards, > Ivy Tang > > > -- Jonathan Ellis Project Chair, Apache Cassandra co-founder of Riptano, the source for professional Cassandra support http://riptano.com
