Mongodb地理空间查询未报告球形包裹错误，但返回了奇怪的结果

Question

I have a weird behavior when querying geospatial data.

From the doc :

We don't currently handle wrapping at the poles or at the transition from -180° to +180° longitude, however we detect when a search would wrap and raise an error.

However I have one object at [179,0] and if I query for objects near [-179,0] with a max distance of 0.9, the object is returned and the computed distance is 2 degrees. No error is raised.

If I query for the same location, but with a max distance of 1.0 the object is not returned and still no error.

Is this a bug or do I miss something? I could not find any reported bug about that on jira.

PRIMARY> version()
version: 2.0.7
PRIMARY> db.runCommand({geoNear:"GeoBug",near:[-179,0],spherical:true,maxDistance:1.0})
{
  "ns" : "mydb.GeoBug",
  "near" : "0100000000000000100010100010100000000000100010100010",
  "results" : [
    {
      "dis" : 0.03490658503988567, (2 degrees)
      "obj" : {
        "_id" : ObjectId("5098e71b744eca2df1b325f2"),
        "location" : {
          "lonlat" : [
            179,
            0
          ]
        }
      }
    }
  ],
  "stats" : {
    "time" : 0,
    "btreelocs" : 0,
    "nscanned" : 2,
    "objectsLoaded" : 1,
    "avgDistance" : 0.03490658503988567,
    "maxDistance" : 0.03490689563235392
  },
  "ok" : 1
}
PRIMARY> db.runCommand({geoNear:"GeoBug",near:[-179,0],spherical:true,maxDistance:0.9})
{
  "ns" : "mydb.GeoBug",
  "near" : "0100000000000000100010100010100000000000100010100010",
  "results" : [ ],
  "stats" : {
    "time" : 0,
    "btreelocs" : 0,
    "nscanned" : 1,
    "objectsLoaded" : 0,
    "avgDistance" : NaN,
    "maxDistance" : 0
  },
  "ok" : 1
}

Answer 1

I've tried this with both 2.0.7 and 2.2.1 and I get some different behavior than you do.

I did this for both versions:

t = db.test
t.drop()
t.insert({geo: [179,0]})
t.ensureIndex({geo: "2d"})

In 2.0.7, I ran:

db.runCommand({geoNear:"test", near:[-179,0], spherical:true, maxDistance:1.0})
db.runCommand({geoNear:"test", near:[-179,0], spherical:true, maxDistance:0.9})

and each returned a result.

However, for 2.2.1, neither search returned a result. This suggests that there is no wrapping around in 2.2.1 as documented, but there is wrapping around in 2.0.7.

Answer 2

It's very ridiculous, but try with 'sperical' instead of 'spherical'.

It's working for my case.

I don't know why, and now I'm looking for the answers, but I couldn't find any.