I believe that the key reason is souped up performance for most recent data. And yes, "an intelligent flush" leaves you vulnerable to some data loss.
/*********************** sent from my android...please pardon occasional typos as I respond @ the speed of thought ************************/ On May 22, 2011 11:01 AM, "Yang" <teddyyyy...@gmail.com> wrote: Thanks, I did read through that pdf doc, and went through the counters code in 0.8-rc2, I think I understand the logic in that code. in my hypothetical implementation, I am not suggesting to overstep the complicated logic in counters code, since the extra module will still need to enter the increment through StorageProxy.mutate( My_counter.delta=1 ) , so that the logical clock is still handled by the Counters code. the only difference is, as you said, that rainbird collapses many +1 deltas. but my claim is that in fact this "collapsing" is already done by cassandra since the write always hit the memtable first, so collapsing in Cassandra memtable vs collapsing in rainbird memory takes the same time, while rainbird introduces an extra level of caching (I am strongly suspecting that rainbird is vulnerable to losing up to 1minute's worth of data , if the rainbird dies before the writes are flushed to cassandra ---- unless it does implement its own commit log, but that is kind of re-implementing many of the wheels in Cassandra ....) I thought at one time probably the reason was because that from one given url, rainbird needs to create writes on many keys, so that they keys need to go to different Cassandra nodes. but later I found that this can also be done in a module on the coordinator, since the client request first hits a coordinator, instead of the data node, in fact, in a multi-insert case, the coordinator already sends the request to multiple data nodes. the extra module I am proposing simply translates a single insert into multi-insert, and then cassandra takes over from there Thanks Yang On Sun, May 22, 2011 at 3:47 AM, aaron morton <aa...@thelastpickle.com> wrote: > The implementatio...
