[{"name":"Some name","products":[{"product_name":"a"},{"product_name":"b"},{"product_name":"c"}]},{"name":"Some name","products":[{"product_name":"c"},{"product_name":"b"},{"product_name":"a"}]},{"name":"Some name","products":[{"product_name":"a"},{"product_name":"b"}]}]

db.collection.update({"name":"Some name"},{"$addToSet":{"products":{"$each":[{"product_name":"b"},{"product_name":"c"},{"product_name":"a"}]}}},{"upsert":true,"multi":true})