Yes. It greatly increases the splits and the random io. -Tupshin On Jul 2, 2014 6:09 PM, "Clint Kelly" <clint.ke...@gmail.com> wrote:
> Sorry BTW in case what I wrote below is unclear, is the concern that > the Hadoop InputFormat (as an example) will need to have a separate > InputSplit (which corresponds to a "SELECT foo FROM bar WHERE > token(baz) > min AND token(baz) < max") for every vnode instead of for > every token? > > (I assume this would be an increase of several orders of magnitude in > the number of input splits.) > > Best regards, > Clint > > On Wed, Jul 2, 2014 at 6:04 PM, Clint Kelly <clint.ke...@gmail.com> wrote: > > Hi Tupshin, > > > > Thanks for the quick reply. Is the performance concern from the > > Hadoop integration needing to set up separate SELECT operations for > > all of the unique vnode ranges? > > > > Best regards, > > Clint > > > > On Wed, Jul 2, 2014 at 6:00 PM, Tupshin Harper <tups...@tupshin.com> > wrote: > >> For performance reasons, you shouldn't enable vnodes on any > Cassandra/DSE > >> datacenter that is doing hadoop analytics workloads. Other DCs in the > >> cluster can use vnodes. > >> > >> -Tupshin > >> > >> On Jul 2, 2014 5:50 PM, "Clint Kelly" <clint.ke...@gmail.com> wrote: > >>> > >>> Hi everyone, > >>> > >>> Apologies if this is the incorrect forum for a question like this. > >>> > >>> I am going to set up a mixed-workload (real-time and analytics) > >>> installation of DSE 4.5 using bring-your-own Hadoop (BYOH). We are > >>> using CDH 5.0. > >>> > >>> I was reviewing the installation instructions, and I came across the > >>> following comment here: > >>> > >>> > http://www.datastax.com/documentation/datastax_enterprise/4.5/datastax_enterprise/byoh/byohInstall.html > >>> > >>> "6. Observe workload isolation best practices. Do not enable vnodes." > >>> > >>> Does this mean that the use of vnodes is not compatible with a > >>> mixed-workload installation? Or with BYOH? I am confused why this > >>> would be the case. > >>> > >>> If anyone can clarify, I would greatly appreciate it. > >>> > >>> Best regards, > >>> Clint >
