Except then you have to merge results if you want them ordered.
On Fri, Jul 25, 2014 at 2:15 PM, Kevin Burton <bur...@spinn3r.com> wrote: > Ah.. ok. Nice. That should work. Parallel dispatch on the client would > work too.. using async. > > > On Fri, Jul 25, 2014 at 1:37 PM, Laing, Michael <michael.la...@nytimes.com > > wrote: > >> We use IN (keeping the number down). The coordinator does parallel >> dispatch AND applies ORDERED BY to the aggregate results, which we would >> otherwise have to do ourselves. Anyway, worth it for us. >> >> ml >> >> >> On Fri, Jul 25, 2014 at 1:24 PM, Kevin Burton <bur...@spinn3r.com> wrote: >> >>> Perhaps the best strategy is to have the datastax java-driver do this >>> and I just wait or each result individually. This will give me parallel >>> dispatch. >>> >>> >>> On Fri, Jul 25, 2014 at 11:40 AM, Graham Sanderson <gra...@vast.com> >>> wrote: >>> >>>> Of course the driver in question is allowed to be smarter and can do so >>>> if use use a ? parameter for a list or even individual elements >>>> >>>> I'm not sure which if any drivers currently do this but we plan to >>>> combine this with token aware routing in our scala driver in the future >>>> >>>> Sent from my iPhone >>>> >>>> On Jul 25, 2014, at 1:14 PM, DuyHai Doan <doanduy...@gmail.com> wrote: >>>> >>>> Nope. Select ... IN() sends one request to a coordinator. This >>>> coordinator dispatch the request to 50 nodes as in your example and waits >>>> for 50 responses before sending back the final result. As you can guess >>>> this approach is not optimal since the global request latency is bound to >>>> the slowest latency among 50 nodes. >>>> >>>> On the other hand if you use async feature from the native protocol, >>>> you client will issue 50 requests in parallel and the answers arrive as >>>> soon as they are fetched from different nodes. >>>> >>>> Clearly the only advantage of using IN() clause is ease of query. I >>>> would advise to use IN() only when you have a "few" values, not 50. >>>> >>>> >>>> On Fri, Jul 25, 2014 at 8:08 PM, Kevin Burton <bur...@spinn3r.com> >>>> wrote: >>>> >>>>> Say I have about 50 primary keys I need to fetch. >>>>> >>>>> I'd like to use parallel dispatch. So that if I have 50 hosts, and >>>>> each has record, I can read from all 50 at once. >>>>> >>>>> I assume cassandra does the right thing here ? I believe it does… at >>>>> least from reading the docs but it's still a bit unclear. >>>>> >>>>> Kevin >>>>> >>>>> -- >>>>> >>>>> Founder/CEO Spinn3r.com >>>>> Location: *San Francisco, CA* >>>>> blog: http://burtonator.wordpress.com >>>>> … or check out my Google+ profile >>>>> <https://plus.google.com/102718274791889610666/posts> >>>>> <http://spinn3r.com> >>>>> >>>>> >>>> >>> >>> >>> -- >>> >>> Founder/CEO Spinn3r.com >>> Location: *San Francisco, CA* >>> blog: http://burtonator.wordpress.com >>> … or check out my Google+ profile >>> <https://plus.google.com/102718274791889610666/posts> >>> <http://spinn3r.com> >>> >>> >> > > > -- > > Founder/CEO Spinn3r.com > Location: *San Francisco, CA* > blog: http://burtonator.wordpress.com > … or check out my Google+ profile > <https://plus.google.com/102718274791889610666/posts> > <http://spinn3r.com> > >
