An example of the MongoDB aggregation framework

console.js

use wlw;

db.wlw.drop();

heading1 = { _id: 10001, name: "Schrauben" , company_counts: { "de":0, "at":9 }, keywords: ["Metall", "Gewinde", "Konstruktion"] };
heading2 = { _id: 10002, name: "Rohre"     , company_counts: { "de":1, "at":3 }, keywords: ["Metall", "Profil" , "Konstruktion"] };
heading3 = { _id: 10003, name: "Holzballen", company_counts: { "de":3, "at":0 }, keywords: ["Holz"  , "Bau"    , "Konstruktion"] };

db.wlw.insert(heading1);
db.wlw.insert(heading2);
db.wlw.insert(heading3);

db.wlw.find();

//db.wlw.aggregate([ {}, {}, {} ]);

db.wlw.aggregate([{$match:{"name":"Schrauben"}}]);

output.js

{
	"result" : [
		{
			"_id" : 10001,
			"name" : "Schrauben",
			"company_counts" : {
				"de" : 0,
				"at" : 9
			},
			"keywords" : [
				"Metall",
				"Gewinde",
				"Konstruktion"
			]
		}
	],
	"ok" : 1
}