couchdb - 无法运行 Mango 查询

Question

这是我的查询：

{
   "selector": {
      "_id": {
         "$regex": "^rati"  //need to find all documents in ratings partition
      }
   },
   "fields": [
      "MovieID",
      "UserId",
      "Rating"
   ],
   "limit": 10,
   "sort": [
      {
         "MovieID": "asc"
      }
   ]
}

当我运行这个查询时，我有这个错误：Error running query. Reason: (no_usable_index) No global index exists for this sort, try indexing by the sort fields.

如果我删除

"sort": [
          {
             "MovieID": "asc"
          }
       ]

一切正常。老实说，我快疯了，我不明白我错在哪里。

我试过这个查询：

{
   "selector": {
      "_id": {
         "$regex": "^rati"
      },
      "MovieID": {
         "$gte": 0
      }
   },
   "fields": [
      "_id",
      "MovieID",
      "UserId",
      "Rating"
   ],
   "limit": 10,
   "sort": [
      {
         "_id": "asc"
      }
   ]
}

但是是一样的。

Answer 1

您需要为该字段创建一个索引MovieID

//Create via POST /db/_index HTTP/1.1 Content-Type: application/json

{
    "index": {
        "fields": ["MovieID"]
    },
    "name" : "MovieID-index",
    "type" : "json"
}

然后将该字段MovieID作为选择器的一部分包含在内。

在这里试试这个：

{
   "selector": {
      "_id": {
         "$regex": "^rati"  //need to find all documents in ratings partition
      },
      "MovieID": {"$gte": 0} // include MovieID, If the ID is non-numeric change the selecor type.
   },
   "fields": [
      "MovieID",
      "UserId",
      "Rating"
   ],
   "limit": 10,
   "sort": [
      {
         "MovieID": "asc"
      }
   ]
}