latest_10_keys.rb

require 'rubygems'
require 'riak'
require 'json'
require 'benchmark'
require 'pp'

$client = Riak::Client.new :protocol => :pbc

def latest_10_via_values
  mr = Riak::MapReduce.new($client).
    add("events").
    map(<<-MAP).
function(v) {
  var data = Riak.mapValuesJson(v)[0]
  var epoch_ms = parseInt(data.created_at, 16);
  return [ { time : epoch_ms, key : v.key } ];
}
    MAP
  reduce(<<-REDUCE, :keep => true)
function(vs) {
  var vs_sorted = vs.sort(function(a,b){ return b.time - a.time; });
  return vs_sorted.slice(0,10);
}
  REDUCE

  results = mr.run
  puts results
end

puts Benchmark.measure { latest_10_via_values }