MapReduce filtering question

Parker Thompson parkert at
Fri Nov 19 23:54:32 EST 2010

Thanks, a few questions inline...

On Fri, Nov 19, 2010 at 2:43 PM, Sean Cribbs <sean at> wrote:

class Riak::Alternative
>  include Ripple::Document
>  many :visitors, :class_name => "Riak::Visitor"
>   property :alternative_id, Integer, :presence => true
>   key_on :alternative_id
> end

If I expect to be writing large numbers of visitor->alternatives links is it
performant to be writing them all as links on one object, as opposed to
creating many experience docs each with a link ?  Naïvely I would assume
this might less evenly distribute write load or degrade as the size of the
Link data grows.  Does this matter?

> ########
> def visitors_who_shared
>     add("riak_alternatives", ar_id.to_s).
>    link(:bucket => 'riak_visitors').
>    map(link_to_events_forward_visitor).
>    map(map_share_events_to_visitor).
>    reduce(["riak_kv_mapreduce", "reduce_set_union"]).
>    map(map_identity, :keep => true).
>    run
> end

Ah, I was looking for a set_union.  Is there a full list of these functions
hiding somewhere?


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