Question

I have several geo queries which look similar to the below example. They are not only a point in Poly query but have other aspects to it.

Query:

{
"point": {
    "$within": {
        "$polygon": [
            [
                41.878335,
                -87.627319999999997
            ],
            [
                41.877602000000003,
                -87.627319999999997
            ],
            [
                41.879672999999997,
                -87.627031000000002
            ],
            [
                41.878723999999998,
                -87.627204000000006
            ],
            [
                41.878507999999997,
                -87.627262000000002
            ],
            [
                41.878335,
                -87.627262000000002
            ]
        ]
    }
},
"MYLISTING": {
    "$in": [
        "All"
    ]
},
"SUPPORT": {
    "$in": [
        "Y"
    ]
},
"TYPE": {
    "$in": [
        "Food"
    ]
}
}

To help make these quicker I added each of the other items to an index making it:

{   "v" : 1,
    "key" : {
        "point" : "2d",
        "MYLISTING" : 1,
        "SUPPORT" : 1,
        "TYPE" : 1
    },
    "ns" : "mydb.collection",
    "name" : "point_2d_MYLISTING_1_SUPPORT_1_TYPE_1"
}

However when doing an explain on this, it never seems to be using this index, it’s simply using the other index I have which is only the point:2d index initially created.

is there some mis-understandign I’m having here?

Answer 1

You can only have one geo index – now you have two, where one of the parts is part of your compound index. The limitation is mentioned in the documentation: http://api.mongodb.org/wiki/current/Geospatial%20Indexing.html#GeospatialIndexing-CreatingtheIndex

The solution would be to simply drop the index that you have on just the spatial field:

db.yourCollection.dropIndex( { point: '2d' };

When you then run your query, with explain(), you see which index is now used again – and in this case, that should be the compound index. Also make sure, that the geo spatial field is the first part of your compound index as described here: http://api.mongodb.org/wiki/current/Geospatial%20Indexing.html#GeospatialIndexing-CompoundIndexes