Agree to aaron's point. But still I think there are ways to overcome this problem, as I believe that the row-scan use-case is very important. One simple ( but expensive ) approach could be to duplicate the rows with RP tokens on primary node, which will be used only in case of repairs.
Any thoughts ? Thanks, Prasenjit On 7/20/12, aaron morton <aa...@thelastpickle.com> wrote: > Repair and token moves work on ranges of Tokens, not row keys. These > operations need to scan through all the rows in the token range. > > Ordering the rows by row key locally would mean that every row on the node > would have to be scanned to find the ones whose token was in the required > token range. > > Cheers > > ----------------- > Aaron Morton > Freelance Developer > @aaronmorton > http://www.thelastpickle.com > > On 20/07/2012, at 4:46 AM, prasenjit mukherjee wrote: > >> When a request for token change is issued ( via nodetool ) then on >> what basis a node will move some of its rows to other node, as there >> will be no way to scan rows based on MD5 hash in a given node ( if the >> keys are not prefixed with MD5 hash ) >> >> On Thu, Jul 19, 2012 at 1:43 PM, Patrik Modesto >> <patrik.mode...@gmail.com> wrote: >>> Hi Prasenjit, >>> >>> I don't see the need to recalculate anything. One key has a one MD5 >>> hash, it doesn't change. Just use the hash to select a node, than just >>> the plain key. Can you elaborate on the redistribution please? >>> >>> Regards, >>> P. >>> >>> On Thu, Jul 19, 2012 at 9:09 AM, prasenjit mukherjee >>> <prasen....@gmail.com> wrote: >>>> The probem could be while redistributing the tokens. In that case the >>>> hashes has to be recalculated on each fo the candidate node. >>>> >>>> -Thanks, >>>> Prasenjit >>>> >>>> On Thu, Jul 19, 2012 at 12:19 PM, Patrik Modesto >>>> <patrik.mode...@gmail.com> wrote: >>>>> Hi, >>>>> >>>>> I know that RandomPartitioner does MD5 of a key and the MD5 is then >>>>> used for key distribution AND key ordering. I was just wondering if >>>>> it's possible to have RandomPartitioner just for key distribution and >>>>> OrderedPartitioner just for per-node key ordering. That would solve >>>>> the often requested key scan feature. >>>>> >>>>> Regards, >>>>> Patrik > > -- Sent from my mobile device
