The brewery_beers view outputs a composite list of breweries and beers they brew by using the view output format to create a 'fake' join, as detailed in Section 9.9.10, “Solutions for Simulating Joins”. This outputs the brewery ID for brewery document types, and the brewery ID and beer ID for beer document types:

function(doc, meta) {
  switch(doc.type) {
  case "brewery":
    emit([meta.id]);
    break;
  case "beer":
    if (doc.brewery_id) {
      emit([doc.brewery_id, meta.id]);
    }
    break;
  }
}

The raw JSON output from the view:

{
   "total_rows" : 7315,
   "rows" : [
      {
         "value" : null,
         "id" : "110f0013c9",
         "key" : [
            "110f0013c9"
         ]
      },
      {
         "value" : null,
         "id" : "110fdd305e",
         "key" : [
            "110f0013c9",
            "110fdd305e"
         ]
      },
      {
         "value" : null,
         "id" : "110fdd3d0b",
         "key" : [
            "110f0013c9",
            "110fdd3d0b"
         ]
      },
…
      {
         "value" : null,
         "id" : "110fdd56ff",
         "key" : [
            "110f0013c9",
            "110fdd56ff"
         ]
      },
      {
         "value" : null,
         "id" : "110fe0aaa7",
         "key" : [
            "110f0013c9",
            "110fe0aaa7"
         ]
      },
      {
         "value" : null,
         "id" : "110f001bbe",
         "key" : [
            "110f001bbe"
         ]
      }
   ]
}

The output could be combined with the corresponding brewery and beer data to provide a list of the beers at each brewery.