> toJson(db.examples.all().explain(), true);
{
  "cursor" : "query>collection",
  "scannedIndexEntries" : 0,
  "scannedDocuments" : 87,
  "matchedDocuments" : 33,
  "runtime" : 0.017073869705200195,
  "query" : {
    "type" : "collection",
    "collection" : "examples"
  }
}

> toJson(db.examples.all().document("9496015:11126645").explain(), true);
{
  "cursor" : "query>primary",
  "scannedIndexEntries" : 1,
  "scannedDocuments" : 0,
  "matchedDocuments" : 1,
  "runtime" : 0.003036022186279297,
  "query" : {
    "type" : "document",
    "identfier" : 11126645,
    "collection" : "examples"
  }
}

> toJson(db.examples.all().limit(100).document("9496015:11126645").explain(), true);
{
  "cursor" : "query>collection>limit>full-scan[document]",
  "scannedIndexEntries" : 0,
  "scannedDocuments" : 88,
  "matchedDocuments" : 67,
  "runtime" : 0.04597210884094238,
  "query" : {
    "type" : "document",
    "identfier" : 11126645,
    "operand" : {
      "type" : "limit",
      "limit" : 100,
      "operand" : {
        "type" : "collection",
        "collection" : "examples"
      }
    }
  }
}