A bit more digging has shed some light on the issue I'm seeing. I am using a custom built protocol buffer client, and it would appear that Riak is sending back more than 1 response for the map reduce job, which seems odd to me.
The first response contains - The expected content payload - Has the "has_done" property set to false - Has the "done" property set to false - Has the "has_response" property set to true The second response contains - No data payload - "has_done" property set to true - "done" property set to true - "has_response" property set to false I would have expected only one response, with all three properties set to true. At any rate, I'll look a bit more at my API to figure out why that second response is slowing things down. At any rate, if I manually short circuit out of my response fetching the actual response time of the first response packet received is is much closer to the double fetch scenario (it's 0.002245 seconds, twice as slow as a single fetch, but much faster). I haven't yet poked around to see if it's my code that's slow or Riak that's slow in sending the second response yet. I would have to hazard a guess and say it's Riak (but that's just a guess). I would further suppose that Riak has to coordinate between all nodes (even when there's one) for mapreduce, and the delay in the second packet is related to that coordination. Again, just a guess. Cheers, Mark Steele Bering Media Inc. On Tue, Aug 30, 2011 at 3:06 PM, Mark Steele <mste...@beringmedia.com>wrote: > I'm actually testing with an object that has only one link as that's my > use-case. > > In testing, 2 separate gets is way faster than using a map-reduce > link-walk, which is disappointing :( > > I'm also testing on a one node cluster, and my bucket has a N/R/W=1. I was > thinking that the reduction in network hops would outweigh the map reduce > overhead, but apparently that's not the case. > > Simple get (one value) : 0.000741 > Multiget linkwalk (get one object, then link walk in php) : 0.001567 > Linkwalk (map reduce): 0.041994 > > The map phase does not significantly change anything as far as performance. > > In case it matters, I'm testing against the latest riak code on github. > > Cheers, > > Mark Steele > Bering Media Inc. > > On Tue, Aug 30, 2011 at 3:00 PM, Jonathan Langevin < > jlange...@loomlearning.com> wrote: > >> Good catch Kev. >> >> Mark, If you run the same operation with map removed, what is the >> performance at that point?* >> >> <http://www.loomlearning.com/> >> Jonathan Langevin >> Systems Administrator >> Loom Inc. >> Wilmington, NC: (910) 241-0433 - jlange...@loomlearning.com - >> www.loomlearning.com - Skype: intel352 >> * >> >> >> >> On Tue, Aug 30, 2011 at 2:45 PM, Kev Burns <kevburn...@gmail.com> wrote: >> >>> Mark, >>> >>> That's not just a link walk, you're also performing a map operation >>> there. >>> >>> $client->add($bucketname, 'linkkey1')-> >>> link()-> >>> map(array("riak_kv_mapreduce", "map_object_value")) -> >>> run(); >>> >>> >>> If the expected number of returned objects is small, performing the map >>> phase in PHP may be faster. >>> >>> - Kev >>> c: +001 (650) 521-7791 >>> >>> >>> On Tue, Aug 30, 2011 at 7:31 AM, Mark Steele <mste...@beringmedia.com>wrote: >>> >>>> Hi folks, >>>> >>>> Just want to know if I'm doing something obviously dumb here. >>>> >>>> First the (PHP) code (Sorry of the API is different from the official >>>> API, we're using a heavily modified version): >>>> >>>> <snip> >>>> $obj1 = $bucket->newObject('linkkey1', array('link1')); >>>> $obj2 = $bucket->newObject('linkkey2', 'dataforlinkkey2'); >>>> $obj1->addLink($obj2); >>>> $obj2->addLink($obj1); >>>> $obj1->store(); >>>> $obj2->store(); >>>> >>>> $start = microtime(true); >>>> $blargh = $bucket->get('linkkey2'); >>>> $end = microtime(true); >>>> printf("Took : %04f\n",$end - $start); >>>> >>>> $start = microtime(true); >>>> $result = >>>> $client->add($bucketname, 'linkkey1')-> >>>> link()-> >>>> map(array("riak_kv_mapreduce", "map_object_value")) -> >>>> run(); >>>> foreach ($result as $data) { >>>> //var_dump($data); >>>> } >>>> $end = microtime(true); >>>> printf("Took : %04f\n",$end - $start); >>>> <snip> >>>> >>>> So here's what I'm seeing: >>>> >>>> The simple key fetch takes 0.000661 seconds to execute, whereas the >>>> link-walk takes 0.042043. Ouch. Quite a bit slower. Any ways to speed >>>> this up? >>>> >>>> Cheers, >>>> >>>> Mark Steele >>>> Bering Media Inc. >>>> >>>> >>>> _______________________________________________ >>>> riak-users mailing list >>>> riak-users@lists.basho.com >>>> http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com >>>> >>>> >>> >>> _______________________________________________ >>> riak-users mailing list >>> riak-users@lists.basho.com >>> http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com >>> >>> >> >
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