Do you get the results in both cases? -Alexander Sicular
@siculars http://siculars.posterous.com On Nov 30, 2011, at 4:28 PM, Sajithkumar Kizhakkiniyil wrote: > Hello > Probably my understanding of M/R might be wrong. But I am getting drastic > performance difference when running secondary index query on PB with map and > reduce function in different order. > If my understanding is correct a reduce phase with > riak_kv_mapreduce.reduce_identity is needed for secondary index query. I > added one map phase to get the value instead of the key > > But if I send the reduce before the map as you see in the map reduce payload > JSON the values are return much faster than the other way. In my test it 251 > ms vs 700ms. Anyone can explain this behavior. > > Reduce before map (Faster) > ------- > {"inputs":{"index":"PERFTEST_INDEX_NAME_bin","bucket":"_ITEST_SI_BUCKET","key":"PERFTEST_INDEX_VALUE"},"query":[{"reduce":{"arg":"{reduce_phase_only_1, > > true}","module":"riak_kv_mapreduce","language":"erlang","keep":false,"function":"reduce_identity"}},{"map":{"source":"function(value,keyData,arg){ > return [value.values[0].data]; }","language":"javascript","keep":true}}]} > > Map before reduce (Slower) > -------------- > {"inputs":{"index":"PERFTEST_INDEX_NAME_bin","bucket":"_ITEST_SI_BUCKET","key":"PERFTEST_INDEX_VALUE"},"query":[{"map":{"source":"function(value,keyData,arg){ > return [value.values[0].data]; > }","language":"javascript","keep":true}},{"reduce":{"arg":"{reduce_phase_only_1, > > true}","module":"riak_kv_mapreduce","language":"erlang","keep":false,"function":"reduce_identity"}}]} > > > This message is private and confidential. If you have received it in error, > please notify the sender and remove it from your system. > > _______________________________________________ > riak-users mailing list > riak-users@lists.basho.com > http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
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