相关疑难解决方法(0)

我在mongodb中有一组文档,如下所示:

{
    "_id" : ObjectId("558cd1c4bf46acde47a0d4f6"),
    "content" : "That is very good",
    "createTime" : NumberLong("1435292100235"),
    "deleted" : false,
    "parent" : "",
    "poiId" : "538318500cf2e33469a2d819",
    "poiType" : "event",
    "role" : "user",
    "threadId" : "e9f800dc3c6dca0b98604bc08ad5ffec17c2aba1",
    "thumbsUp" : 0,
    "userId" : "53a85640f66cce8abfdb433e5215c8d981d0df86"
}
{
    "_id" : ObjectId("558cd375bf46acde47a0d4f7"),
    "content" : "That is very good",
    "createTime" : NumberLong("1435292533764"),
    "deleted" : false,
    "parent" : "558cd1c4bf46acde47a0d4f6",
    "poiId" : "538318500cf2e33469a2d819",
    "poiType" : "event",
    "role" : "user",
    "threadId" : "e9f800dc3c6dca0b98604bc08ad5ffec17c2aba1",
    "thumbsUp" : 0,
    "userId" : "53a85640f66cce8abfdb433e5215c8d981d0df86"
}
{
    "_id" : …