MongoDB MapReduce Example

mon3.php

<?php
 $conn = new Mongo('localhost');

  // access database
  $db = $conn->benchmark;

  // access collection
  $stats = $db->coll3;

$map = new MongoCode("function() { emit(this.shop_hash,1); }");
$reduce = new MongoCode("function(k, vals) { ".
    "var sum = 0;".
    "for (var i in vals) {".
        "sum += vals[i];". 
    "}".
    "return sum; }");

$clicks = $db->command(array(
    "mapreduce" => "coll3", 
    "map" => $map,

    "limit" => 100000,
    "reduce" => $reduce,
    "out" => array("replace" => "eventCounts"),
    "verbose" => true
));
$statsResult = $db->selectCollection($clicks['result'])->find();

foreach ($statsResult as $stat) {
    echo "{$stat['_id']} had {$stat['value']} click(s).\n";
}

?>