MongoDB3.2.10 geo Query Too Slow

  mongodb, question

Version

Mongo3.2.10

Problem

Geo query under dense set returned the latest 30 records, and 20000+ records need to be scanned.
For the same point set, try to establish 2d index and 2dsphere index query, and the execution efficiency is not much different.

execute statement

Execution environment for statement 1

2d index

{
 "v" : 1,
 "key" : {
 "lag" : "2d"
 },
 "name" : "lag",
 "min" : -180,
 "ns" : "mobike_default.mBKBikeInfo",
 "bits" : 26,
 "max" : 180
 },
db.coll.find({lag:{'$nearSphere':[120.993965,31.449034 ], '$maxDistance':7.83927971443699e-05*2}}).limit(30).explain(true)

MongoDB shell version: 3.2.8
connecting to: 10.108.93.135:7004/admin
{

"queryPlanner" : {
    "plannerVersion" : 1,
    "namespace" : "{db}.{coll}",
    "indexFilterSet" : false,
    "parsedQuery" : {
        "lag" : {
            "$nearSphere" : [
                120.993965,
                31.449034
            ],
            "$maxDistance" : 0.0000783927971443699
        }
    },
    "winningPlan" : {
        "stage" : "LIMIT",
        "limitAmount" : 30,
        "inputStage" : {
            "stage" : "GEO_NEAR_2D",
            "keyPattern" : {
                "lag" : "2d"
            },
            "indexName" : "lag",
            "inputStages" : [
                {
                    "stage" : "FETCH",
                    "inputStage" : {
                        "stage" : "IXSCAN",
                        "keyPattern" : {
                            "lag" : "2d"
                        },
                        "indexName" : "lag",
                        "isMultiKey" : false,
                        "isUnique" : false,
                        "isSparse" : false,
                        "isPartial" : false,
                        "indexVersion" : 1,
                        "direction" : "forward",
                        "indexBounds" : {
                            "lag" : [
                                "[BinData(128, E33C11D200000000), BinData(128, E33C11D2FFFFFFFF)]",
                                "[BinData(128, E33C11D300000000), BinData(128, E33C11D33FFFFFFF)]",
                                "[BinData(128, E33C11D360000000), BinData(128, E33C11D36FFFFFFF)]",
                                "[BinData(128, E33C11D370000000), BinData(128, E33C11D37FFFFFFF)]",
                                "[BinData(128, E33C11D380000000), BinData(128, E33C11D3BFFFFFFF)]",
                                "[BinData(128, E33C11D3C0000000), BinData(128, E33C11D3FFFFFFFF)]",
                                "[BinData(128, E33C11D688000000), BinData(128, E33C11D68BFFFFFF)]",
                                "[BinData(128, E33C11D6A0000000), BinData(128, E33C11D6AFFFFFFF)]",
                                "[BinData(128, E33C11D800000000), BinData(128, E33C11D8FFFFFFFF)]",
                                "[BinData(128, E33C11D900000000), BinData(128, E33C11D9FFFFFFFF)]",
                                "[BinData(128, E33C11DA10000000), BinData(128, E33C11DA1FFFFFFF)]",
                                "[BinData(128, E33C11DA40000000), BinData(128, E33C11DA7FFFFFFF)]",
                                "[BinData(128, E33C11DB00000000), BinData(128, E33C11DB3FFFFFFF)]",
                                "[BinData(128, E33C11DB40000000), BinData(128, E33C11DB7FFFFFFF)]",
                                "[BinData(128, E33C11DC00000000), BinData(128, E33C11DC3FFFFFFF)]",
                                "[BinData(128, E33C11DC80000000), BinData(128, E33C11DCBFFFFFFF)]"
                            ]
                        }
                    }
                },
                {
                    "stage" : "FETCH",
                    "inputStage" : {
                        "stage" : "IXSCAN",
                        "keyPattern" : {
                            "lag" : "2d"
                        },
                        "indexName" : "lag",
                        "isMultiKey" : false,
                        "isUnique" : false,
                        "isSparse" : false,
                        "isPartial" : false,
                        "indexVersion" : 1,
                        "direction" : "forward",
                        "indexBounds" : {
                            "lag" : [ ]
                        }
                    }
                },
                {
                    "stage" : "FETCH",
                    "inputStage" : {
                        "stage" : "IXSCAN",
                        "keyPattern" : {
                            "lag" : "2d"
                        },
                        "indexName" : "lag",
                        "isMultiKey" : false,
                        "isUnique" : false,
                        "isSparse" : false,
                        "isPartial" : false,
                        "indexVersion" : 1,
                        "direction" : "forward",
                        "indexBounds" : {
                            "lag" : [ ]
                        }
                    }
                },
                {
                    "stage" : "FETCH",
                    "inputStage" : {
                        "stage" : "IXSCAN",
                        "keyPattern" : {
                            "lag" : "2d"
                        },
                        "indexName" : "lag",
                        "isMultiKey" : false,
                        "isUnique" : false,
                        "isSparse" : false,
                        "isPartial" : false,
                        "indexVersion" : 1,
                        "direction" : "forward",
                        "indexBounds" : {
                            "lag" : [
                                "[BinData(128, E33C11D340000000), BinData(128, E33C11D34FFFFFFF)]",
                                "[BinData(128, E33C11D350000000), BinData(128, E33C11D35FFFFFFF)]",
                                "[BinData(128, E33C11D680000000), BinData(128, E33C11D683FFFFFF)]",
                                "[BinData(128, E33C11D684000000), BinData(128, E33C11D687FFFFFF)]",
                                "[BinData(128, E33C11D68C000000), BinData(128, E33C11D68FFFFFFF)]"
                            ]
                        }
                    }
                },
                {
                    "stage" : "FETCH",
                    "inputStage" : {
                        "stage" : "IXSCAN",
                        "keyPattern" : {
                            "lag" : "2d"
                        },
                        "indexName" : "lag",
                        "isMultiKey" : false,
                        "isUnique" : false,
                        "isSparse" : false,
                        "isPartial" : false,
                        "indexVersion" : 1,
                        "direction" : "forward",
                        "indexBounds" : {
                            "lag" : [ ]
                        }
                    }
                },
                {
                    "stage" : "FETCH",
                    "inputStage" : {
                        "stage" : "IXSCAN",
                        "keyPattern" : {
                            "lag" : "2d"
                        },
                        "indexName" : "lag",
                        "isMultiKey" : false,
                        "isUnique" : false,
                        "isSparse" : false,
                        "isPartial" : false,
                        "indexVersion" : 1,
                        "direction" : "forward",
                        "indexBounds" : {
                            "lag" : [
                                "[BinData(128, E33C11CD40000000), BinData(128, E33C11CD7FFFFFFF)]",
                                "[BinData(128, E33C11D690000000), BinData(128, E33C11D69FFFFFFF)]",
                                "[BinData(128, E33C11D6B0000000), BinData(128, E33C11D6BFFFFFFF)]",
                                "[BinData(128, E33C11DA00000000), BinData(128, E33C11DA0FFFFFFF)]",
                                "[BinData(128, E33C11DA20000000), BinData(128, E33C11DA2FFFFFFF)]",
                                "[BinData(128, E33C11DA30000000), BinData(128, E33C11DA3FFFFFFF)]"
                            ]
                        }
                    }
                },
                {
                    "stage" : "FETCH",
                    "inputStage" : {
                        "stage" : "IXSCAN",
                        "keyPattern" : {
                            "lag" : "2d"
                        },
                        "indexName" : "lag",
                        "isMultiKey" : false,
                        "isUnique" : false,
                        "isSparse" : false,
                        "isPartial" : false,
                        "indexVersion" : 1,
                        "direction" : "forward",
                        "indexBounds" : {
                            "lag" : [
                                "[BinData(128, E33C11C7FC000000), BinData(128, E33C11C7FFFFFFFF)]",
                                "[BinData(128, E33C11CDD0000000), BinData(128, E33C11CDDFFFFFFF)]",
                                "[BinData(128, E33C11D62AA00000), BinData(128, E33C11D62AAFFFFF)]",
                                "[BinData(128, E33C11DE00000000), BinData(128, E33C11DE03FFFFFF)]"
                            ]
                        }
                    }
                },
                {
                    "stage" : "FETCH",
                    "inputStage" : {
                        "stage" : "IXSCAN",
                        "keyPattern" : {
                            "lag" : "2d"
                        },
                        "indexName" : "lag",
                        "isMultiKey" : false,
                        "isUnique" : false,
                        "isSparse" : false,
                        "isPartial" : false,
                        "indexVersion" : 1,
                        "direction" : "forward",
                        "indexBounds" : {
                            "lag" : [
                                "[BinData(128, E33C11C7C0000000), BinData(128, E33C11C7CFFFFFFF)]",
                                "[BinData(128, E33C11C7D0000000), BinData(128, E33C11C7DFFFFFFF)]",
                                "[BinData(128, E33C11C7E0000000), BinData(128, E33C11C7EFFFFFFF)]",
                                "[BinData(128, E33C11C7F0000000), BinData(128, E33C11C7F3FFFFFF)]",
                                "[BinData(128, E33C11C7F4000000), BinData(128, E33C11C7F7FFFFFF)]",
                                "[BinData(128, E33C11C7F8000000), BinData(128, E33C11C7FBFFFFFF)]",
                                "[BinData(128, E33C11CDC0000000), BinData(128, E33C11CDCFFFFFFF)]",
                                "[BinData(128, E33C11CDE0000000), BinData(128, E33C11CDEFFFFFFF)]",
                                "[BinData(128, E33C11CDF0000000), BinData(128, E33C11CDFFFFFFFF)]",
                                "[BinData(128, E33C11D620000000), BinData(128, E33C11D623FFFFFF)]",
                                "[BinData(128, E33C11D624000000), BinData(128, E33C11D627FFFFFF)]",
                                "[BinData(128, E33C11D628000000), BinData(128, E33C11D628FFFFFF)]",
                                "[BinData(128, E33C11D629000000), BinData(128, E33C11D629FFFFFF)]",
                                "[BinData(128, E33C11D62A000000), BinData(128, E33C11D62A3FFFFF)]",
                                "[BinData(128, E33C11D62A400000), BinData(128, E33C11D62A7FFFFF)]",
                                "[BinData(128, E33C11D62A800000), BinData(128, E33C11D62A8FFFFF)]",
                                "[BinData(128, E33C11D62A900000), BinData(128, E33C11D62A9FFFFF)]",
                                "[BinData(128, E33C11D62AB00000), BinData(128, E33C11D62ABFFFFF)]",
                                "[BinData(128, E33C11D62AC00000), BinData(128, E33C11D62AFFFFFF)]",
                                "[BinData(128, E33C11D62B000000), BinData(128, E33C11D62BFFFFFF)]",
                                "[BinData(128, E33C11D62C000000), BinData(128, E33C11D62FFFFFFF)]",
                                "[BinData(128, E33C11DA80000000), BinData(128, E33C11DABFFFFFFF)]",
                                "[BinData(128, E33C11DAC0000000), BinData(128, E33C11DAFFFFFFFF)]",
                                "[BinData(128, E33C11DB80000000), BinData(128, E33C11DBBFFFFFFF)]",
                                "[BinData(128, E33C11DE04000000), BinData(128, E33C11DE07FFFFFF)]",
                                "[BinData(128, E33C11DE08000000), BinData(128, E33C11DE0BFFFFFF)]",
                                "[BinData(128, E33C11DE0C000000), BinData(128, E33C11DE0FFFFFFF)]"
                            ]
                        }
                    }
                }
            ]
        }
    },
    "rejectedPlans" : [ ]
},
"executionStats" : {
    "executionSuccess" : true,
    "nReturned" : 30,
    "executionTimeMillis" : 185,
    "totalKeysExamined" : 24613,
    "totalDocsExamined" : 24599,
    "executionStages" : {
        "stage" : "LIMIT",
        "nReturned" : 30,
        "executionTimeMillisEstimate" : 160,
        "works" : 24664,
        "advanced" : 30,
        "needTime" : 24633,
        "needYield" : 0,
        "saveState" : 192,
        "restoreState" : 192,
        "isEOF" : 1,
        "invalidates" : 0,
        "limitAmount" : 30,
        "inputStage" : {
            "stage" : "GEO_NEAR_2D",
            "nReturned" : 30,
            "executionTimeMillisEstimate" : 160,
            "works" : 24663,
            "advanced" : 30,
            "needTime" : 24633,
            "needYield" : 0,
            "saveState" : 192,
            "restoreState" : 192,
            "isEOF" : 0,
            "invalidates" : 0,
            "keyPattern" : {
                "lag" : "2d"
            },
            "indexName" : "lag",
            "searchIntervals" : [
                {
                    "minDistance" : 0,
                    "maxDistance" : 305.746339475419,
                    "maxInclusive" : false,
                    "nBuffered" : 5,
                    "nReturned" : 5
                },
                {
                    "minDistance" : 305.746339475419,
                    "maxDistance" : 306.16860060551534,
                    "maxInclusive" : false,
                    "nBuffered" : 0,
                    "nReturned" : 0
                },
                {
                    "minDistance" : 306.16860060551534,
                    "maxDistance" : 307.01312286570794,
                    "maxInclusive" : false,
                    "nBuffered" : 0,
                    "nReturned" : 0
                },
                {
                    "minDistance" : 307.01312286570794,
                    "maxDistance" : 308.70216738609315,
                    "maxInclusive" : false,
                    "nBuffered" : 0,
                    "nReturned" : 0
                },
                {
                    "minDistance" : 308.70216738609315,
                    "maxDistance" : 312.0802564268636,
                    "maxInclusive" : false,
                    "nBuffered" : 0,
                    "nReturned" : 0
                },
                {
                    "minDistance" : 312.0802564268636,
                    "maxDistance" : 318.8364345084046,
                    "maxInclusive" : false,
                    "nBuffered" : 0,
                    "nReturned" : 0
                },
                {
                    "minDistance" : 318.8364345084046,
                    "maxDistance" : 332.3487906714865,
                    "maxInclusive" : false,
                    "nBuffered" : 0,
                    "nReturned" : 0
                },
                {
                    "minDistance" : 332.3487906714865,
                    "maxDistance" : 359.37350299765023,
                    "maxInclusive" : false,
                    "nBuffered" : 24594,
                    "nReturned" : 25
                }
            ],
            "inputStages" : [
                {
                    "stage" : "FETCH",
                    "nReturned" : 5,
                    "executionTimeMillisEstimate" : 0,
                    "works" : 8,
                    "advanced" : 5,
                    "needTime" : 2,
                    "needYield" : 0,
                    "saveState" : 192,
                    "restoreState" : 192,
                    "isEOF" : 1,
                    "invalidates" : 0,
                    "docsExamined" : 5,
                    "alreadyHasObj" : 0,
                    "inputStage" : {
                        "stage" : "IXSCAN",
                        "nReturned" : 5,
                        "executionTimeMillisEstimate" : 0,
                        "works" : 8,
                        "advanced" : 5,
                        "needTime" : 2,
                        "needYield" : 0,
                        "saveState" : 192,
                        "restoreState" : 192,
                        "isEOF" : 1,
                        "invalidates" : 0,
                        "keyPattern" : {
                            "lag" : "2d"
                        },
                        "indexName" : "lag",
                        "isMultiKey" : false,
                        "isUnique" : false,
                        "isSparse" : false,
                        "isPartial" : false,
                        "indexVersion" : 1,
                        "direction" : "forward",
                        "indexBounds" : {
                            "lag" : [
                                "[BinData(128, E33C11D200000000), BinData(128, E33C11D2FFFFFFFF)]",
                                "[BinData(128, E33C11D300000000), BinData(128, E33C11D33FFFFFFF)]",
                                "[BinData(128, E33C11D360000000), BinData(128, E33C11D36FFFFFFF)]",
                                "[BinData(128, E33C11D370000000), BinData(128, E33C11D37FFFFFFF)]",
                                "[BinData(128, E33C11D380000000), BinData(128, E33C11D3BFFFFFFF)]",
                                "[BinData(128, E33C11D3C0000000), BinData(128, E33C11D3FFFFFFFF)]",
                                "[BinData(128, E33C11D688000000), BinData(128, E33C11D68BFFFFFF)]",
                                "[BinData(128, E33C11D6A0000000), BinData(128, E33C11D6AFFFFFFF)]",
                                "[BinData(128, E33C11D800000000), BinData(128, E33C11D8FFFFFFFF)]",
                                "[BinData(128, E33C11D900000000), BinData(128, E33C11D9FFFFFFFF)]",
                                "[BinData(128, E33C11DA10000000), BinData(128, E33C11DA1FFFFFFF)]",
                                "[BinData(128, E33C11DA40000000), BinData(128, E33C11DA7FFFFFFF)]",
                                "[BinData(128, E33C11DB00000000), BinData(128, E33C11DB3FFFFFFF)]",
                                "[BinData(128, E33C11DB40000000), BinData(128, E33C11DB7FFFFFFF)]",
                                "[BinData(128, E33C11DC00000000), BinData(128, E33C11DC3FFFFFFF)]",
                                "[BinData(128, E33C11DC80000000), BinData(128, E33C11DCBFFFFFFF)]"
                            ]
                        },
                        "keysExamined" : 8,
                        "dupsTested" : 0,
                        "dupsDropped" : 0,
                        "seenInvalidated" : 0
                    }
                },
                {
                    "stage" : "FETCH",
                    "nReturned" : 0,
                    "executionTimeMillisEstimate" : 0,
                    "works" : 1,
                    "advanced" : 0,
                    "needTime" : 0,
                    "needYield" : 0,
                    "saveState" : 192,
                    "restoreState" : 192,
                    "isEOF" : 1,
                    "invalidates" : 0,
                    "docsExamined" : 0,
                    "alreadyHasObj" : 0,
                    "inputStage" : {
                        "stage" : "IXSCAN",
                        "nReturned" : 0,
                        "executionTimeMillisEstimate" : 0,
                        "works" : 1,
                        "advanced" : 0,
                        "needTime" : 0,
                        "needYield" : 0,
                        "saveState" : 192,
                        "restoreState" : 192,
                        "isEOF" : 1,
                        "invalidates" : 0,
                        "keyPattern" : {
                            "lag" : "2d"
                        },
                        "indexName" : "lag",
                        "isMultiKey" : false,
                        "isUnique" : false,
                        "isSparse" : false,
                        "isPartial" : false,
                        "indexVersion" : 1,
                        "direction" : "forward",
                        "indexBounds" : {
                            "lag" : [ ]
                        },
                        "keysExamined" : 0,
                        "dupsTested" : 0,
                        "dupsDropped" : 0,
                        "seenInvalidated" : 0
                    }
                },
                {
                    "stage" : "FETCH",
                    "nReturned" : 0,
                    "executionTimeMillisEstimate" : 0,
                    "works" : 1,
                    "advanced" : 0,
                    "needTime" : 0,
                    "needYield" : 0,
                    "saveState" : 192,
                    "restoreState" : 192,
                    "isEOF" : 1,
                    "invalidates" : 0,
                    "docsExamined" : 0,
                    "alreadyHasObj" : 0,
                    "inputStage" : {
                        "stage" : "IXSCAN",
                        "nReturned" : 0,
                        "executionTimeMillisEstimate" : 0,
                        "works" : 1,
                        "advanced" : 0,
                        "needTime" : 0,
                        "needYield" : 0,
                        "saveState" : 192,
                        "restoreState" : 192,
                        "isEOF" : 1,
                        "invalidates" : 0,
                        "keyPattern" : {
                            "lag" : "2d"
                        },
                        "indexName" : "lag",
                        "isMultiKey" : false,
                        "isUnique" : false,
                        "isSparse" : false,
                        "isPartial" : false,
                        "indexVersion" : 1,
                        "direction" : "forward",
                        "indexBounds" : {
                            "lag" : [ ]
                        },
                        "keysExamined" : 0,
                        "dupsTested" : 0,
                        "dupsDropped" : 0,
                        "seenInvalidated" : 0
                    }
                },
                {
                    "stage" : "FETCH",
                    "nReturned" : 0,
                    "executionTimeMillisEstimate" : 0,
                    "works" : 2,
                    "advanced" : 0,
                    "needTime" : 1,
                    "needYield" : 0,
                    "saveState" : 192,
                    "restoreState" : 192,
                    "isEOF" : 1,
                    "invalidates" : 0,
                    "docsExamined" : 0,
                    "alreadyHasObj" : 0,
                    "inputStage" : {
                        "stage" : "IXSCAN",
                        "nReturned" : 0,
                        "executionTimeMillisEstimate" : 0,
                        "works" : 2,
                        "advanced" : 0,
                        "needTime" : 1,
                        "needYield" : 0,
                        "saveState" : 192,
                        "restoreState" : 192,
                        "isEOF" : 1,
                        "invalidates" : 0,
                        "keyPattern" : {
                            "lag" : "2d"
                        },
                        "indexName" : "lag",
                        "isMultiKey" : false,
                        "isUnique" : false,
                        "isSparse" : false,
                        "isPartial" : false,
                        "indexVersion" : 1,
                        "direction" : "forward",
                        "indexBounds" : {
                            "lag" : [
                                "[BinData(128, E33C11D340000000), BinData(128, E33C11D34FFFFFFF)]",
                                "[BinData(128, E33C11D350000000), BinData(128, E33C11D35FFFFFFF)]",
                                "[BinData(128, E33C11D680000000), BinData(128, E33C11D683FFFFFF)]",
                                "[BinData(128, E33C11D684000000), BinData(128, E33C11D687FFFFFF)]",
                                "[BinData(128, E33C11D68C000000), BinData(128, E33C11D68FFFFFFF)]"
                            ]
                        },
                        "keysExamined" : 2,
                        "dupsTested" : 0,
                        "dupsDropped" : 0,
                        "seenInvalidated" : 0
                    }
                },
                {
                    "stage" : "FETCH",
                    "nReturned" : 0,
                    "executionTimeMillisEstimate" : 0,
                    "works" : 1,
                    "advanced" : 0,
                    "needTime" : 0,
                    "needYield" : 0,
                    "saveState" : 192,
                    "restoreState" : 192,
                    "isEOF" : 1,
                    "invalidates" : 0,
                    "docsExamined" : 0,
                    "alreadyHasObj" : 0,
                    "inputStage" : {
                        "stage" : "IXSCAN",
                        "nReturned" : 0,
                        "executionTimeMillisEstimate" : 0,
                        "works" : 1,
                        "advanced" : 0,
                        "needTime" : 0,
                        "needYield" : 0,
                        "saveState" : 192,
                        "restoreState" : 192,
                        "isEOF" : 1,
                        "invalidates" : 0,
                        "keyPattern" : {
                            "lag" : "2d"
                        },
                        "indexName" : "lag",
                        "isMultiKey" : false,
                        "isUnique" : false,
                        "isSparse" : false,
                        "isPartial" : false,
                        "indexVersion" : 1,
                        "direction" : "forward",
                        "indexBounds" : {
                            "lag" : [ ]
                        },
                        "keysExamined" : 0,
                        "dupsTested" : 0,
                        "dupsDropped" : 0,
                        "seenInvalidated" : 0
                    }
                },
                {
                    "stage" : "FETCH",
                    "nReturned" : 0,
                    "executionTimeMillisEstimate" : 0,
                    "works" : 3,
                    "advanced" : 0,
                    "needTime" : 2,
                    "needYield" : 0,
                    "saveState" : 192,
                    "restoreState" : 192,
                    "isEOF" : 1,
                    "invalidates" : 0,
                    "docsExamined" : 0,
                    "alreadyHasObj" : 0,
                    "inputStage" : {
                        "stage" : "IXSCAN",
                        "nReturned" : 0,
                        "executionTimeMillisEstimate" : 0,
                        "works" : 3,
                        "advanced" : 0,
                        "needTime" : 2,
                        "needYield" : 0,
                        "saveState" : 192,
                        "restoreState" : 192,
                        "isEOF" : 1,
                        "invalidates" : 0,
                        "keyPattern" : {
                            "lag" : "2d"
                        },
                        "indexName" : "lag",
                        "isMultiKey" : false,
                        "isUnique" : false,
                        "isSparse" : false,
                        "isPartial" : false,
                        "indexVersion" : 1,
                        "direction" : "forward",
                        "indexBounds" : {
                            "lag" : [
                                "[BinData(128, E33C11CD40000000), BinData(128, E33C11CD7FFFFFFF)]",
                                "[BinData(128, E33C11D690000000), BinData(128, E33C11D69FFFFFFF)]",
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    },
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    "version" : "0.0.1-fake-",
    "gitVersion" : "nogitversion"
},
"ok" : 1

}
bye

Execution environment for statement 2

2dsphere index

{
 "v" : 1,
 "key" : {
 "loc" : "2dsphere"
 },
 "name" : "loc_2dsphere",
 "ns" : "mobike_default.kdytbl",
 "2dsphereIndexVersion" : 3
 }
db.kdytbl.find({loc:{ $nearSphere: { $geometry: { type : "Point",coordinates : [120.993965,31.449034]},$maxDistance:1000}}}).limit(30).explain(true)

MongoDB shell version: 3.2.8
connecting to: 10.108.93.135:7004/admin
{

"queryPlanner" : {
    "plannerVersion" : 1,
    "namespace" : "{db}.{coll}",
    "indexFilterSet" : false,
    "parsedQuery" : {
        "loc" : {
            "$nearSphere" : {
                "$geometry" : {
                    "type" : "Point",
                    "coordinates" : [
                        120.993965,
                        31.449034
                    ]
                },
                "$maxDistance" : 1000
            }
        }
    },
    "winningPlan" : {
        "stage" : "LIMIT",
        "limitAmount" : 1,
        "inputStage" : {
            "stage" : "GEO_NEAR_2DSPHERE",
            "keyPattern" : {
                "loc" : "2dsphere"
            },
            "indexName" : "loc_2dsphere",
            "inputStage" : {
                "stage" : "FETCH",
                "inputStage" : {
                    "stage" : "IXSCAN",
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                    "indexName" : "loc_2dsphere",
                    "isMultiKey" : false,
                    "isUnique" : false,
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                    "indexVersion" : 1,
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"ok" : 1

}

Because 2d index supports spherical query itself, there is a big performance problem, I will mainly look at the second result using 2dsphere index.

Judging from the results of the query explain, the work is normal. In the figure below, the circle is the maxDistance of the query, and the grid is the place where the data is read. The coordinates in the figure are GPS coordinates. If the data are Mars coordinates, there will be deviation in the displayed place.

It may be that the data distribution is very concentrated in this 1km range, but it is far away from the initial point. If $nearSphere cannot find data around the initial point density estimation, it will expand to maxDistance. There is no particularly good method for this point, and the possible solution will also reduce the performance of ordinary queries. It is suggested to download MongoDB Compass and look at the data distribution of loc to confirm this. Or if I can release the location data within a radius of 5 kilometers, I can reproduce it locally, and then I can understand what the problem is. Generally speaking, if the distribution of the starting points of the query is similar to the distribution of the data, on average, the results will not be so extreme.

Finally, explain’s query is not limit 30, but limit 1, but the nature of the problem should be the same. The version you used was compiled by yourself, so you should not change the code related to 2dshpere.

查询覆盖的区域