> Wouldn't this make Writes disk-bound then? I think the documentation may have > been a bit misleading then "Insert-heavy workloads will actually be CPU-bound > in Cassandra before being memory-bound"? What is the source of the quote ?
Cheers ----------------- Aaron Morton Cassandra Consultant New Zealand @aaronmorton http://www.thelastpickle.com On 21/07/2013, at 4:27 AM, Mohammad Hajjat <haj...@purdue.edu> wrote: > Thanks/Shukran, Jon! :) > > Wouldn't this make Writes disk-bound then? I think the documentation may have > been a bit misleading then "Insert-heavy workloads will actually be CPU-bound > in Cassandra before being memory-bound"? > > > > > On Sat, Jul 20, 2013 at 12:12 PM, Jonathan Haddad <jonathan.had...@gmail.com> > wrote: > Everything is written to the commit log. In the case of a crash, cassandra > recovers by replaying the log. > > > On Sat, Jul 20, 2013 at 9:03 AM, Mohammad Hajjat <haj...@purdue.edu> wrote: > Patricia, > > Thanks for the info. So are you saying that the *whole* data is being written > on disk in the commit log, not just some sort of a summary/digest? > I'm writing 10MB objects and I'm noticing high latency (250 milliseconds even > with ANY consistency), so I guess that explains my high delays? > > Thanks, > Mohammad > > > On Fri, Jul 19, 2013 at 2:17 PM, Patricia Gorla <gorla.patri...@gmail.com> > wrote: > Kanwar, > > This is because writes are appends to the commit log, which is stored on > disk, not memory. The commit log is then flushed to the memtable (in memory), > before being written to an sstable on disk. > > So, most of the actions in sending out a write are writing to disk. > > Also see: http://www.datastax.com/docs/1.2/dml/about_writes > > Patricia > > > On Fri, Jul 19, 2013 at 1:05 PM, Kanwar Sangha <kan...@mavenir.com> wrote: > “Insert-heavy workloads will actually be CPU-bound in Cassandra before being > memory-bound” > > > > Can someone explain why the internals of why writes are CPU bound ? > > > > > > > > > > -- > Mohammad Hajjat > Ph.D. Student > Electrical and Computer Engineering > Purdue University > > > > > -- > Mohammad Hajjat > Ph.D. Student > Electrical and Computer Engineering > Purdue University
