//   This query assumes an int range index
//   is configured in the database. It
//   generates some sample data and then
//   performs the aggregation in a separate
//   transaction.

declareUpdate();

for (x=1; x<11; x++) {
  var o = new Object();
  o.int = [];
  for (y=x; y<11; y++) { 
    o.int.push(y);    
  };
  xdmp.documentInsert((x + ".json"), o); 
};

*******
// Then run the following (requires int range index on int):

var item = cts.stddev(
  cts.jsonPropertyReference("int","type=int"),
    ["item-frequency","concurrent"]);
var frag = cts.stddev(
  cts.jsonPropertyReference("int","type=int"),
    ["fragment-frequency","concurrent"]);
var res = new Array();
res.push(item);
res.push(frag);
res;
=>
[2.47206616236522, 2.47206616236522]