Hi, Is the replication factor configurable? For example, Can I configure the replication factor per column-family (e.g., 5 for column-family a and 3 for column-family b).
Also, I am interested about the replication details. Sandeep wrote: "When there's a failure and the #of replicas for a given key goes down, Cassandra does not aggressively create a new copy for the data. The assumption is that the failed node will be replaced soon enough, and work can continue with the other 2 replicas." When and how does cassandra replicate when the replication count of a particular data goes below the replication factor? How does it monitor the replication count of a particular data? -Harold --- On Thu, 6/25/09, Jonathan Ellis <[email protected]> wrote: > From: Jonathan Ellis <[email protected]> > Subject: Re: Question about cassandra (replication) > To: [email protected] > Date: Thursday, June 25, 2009, 10:17 AM > Rather than post the same question > verbatim, it would be more useful > if you explained what you still don't understand after > Alexander and > Sandeep's explanations on the google group. > > (http://groups.google.com/group/cassandra-user/browse_thread/thread/4330e415e959e9d9) > > On Thu, Jun 25, 2009 at 9:11 AM, Harold Lim<[email protected]> > wrote: > > > > Hi All, > > > > I posted a similar message on the google groups page. > Hopefully, I'll get more feedback here. > > > > > > I just started reading about dynamo and Cassandra and > I am thinking > > about possibly using cassandra for my system. > > > > I was reading the dynamo paper and they mentioned > about a preference > > list for a particular key. Is this preference list > configurable? > > > > How does Cassandra choose which nodes are in the > preference list? > > Also, are the number of replica for each key/column > configurable? For > > example, can I set the replication factor per > key/value? > > > > I read that Cassandra has optimistic replication. What > exactly does > > that mean? Underneath the hood, how does cassandra > maintain/detect the > > number of replicas? Does it aggressively replicates an > item, when it > > detects that the number of replica of a particular > item goes below the > > specified repliation factor? > > > > Is the replication strategy (when to replicate, > aggresiveness, etc) > > configurable too? > > > > > > > > > > > > > > Thanks, > > Harold > > > > > > > > >
