Question

I have collection with some daily statistics and I want to use aggregation framework in mongo. Now I faced a problem with sorting/grouping Integer64 (type 18) with each other and I want to ask for some help:

mongos> db.daily_apps_totals.findOne({"_id.appId":{$type:16}})
{
    "_id" : {
            "datetime" : ISODate("2012-08-15T00:00:00Z"),
            "appId" : 243,
            },
    ...
}

mongos> db.daily_apps_totals.aggregate([ {$match: {"_id.datetime":ISODate("2013-01-28T00:00:00Z"), "_id.appId":{$type:16}}},  {$project:{_id:"$_id.appId"}}, {$sort: {_id:1}},{$limit:3}])
{
    "result" : [
            {
                    "_id" : 243
            },
            {
                    "_id" : 243
            },
            {
                    "_id" : 245
            }
    ],
    "ok" : 1
}

Sort works well with Integer32 (type 16), but not with Integer64:

mongos> db.daily_apps_totals.findOne({"_id.appId":{$type:18}})
{
    "_id" : {
            "datetime" : ISODate("2012-08-15T00:00:00Z"),
            "appId" : NumberLong(245),
    },
    ...
}

mongos> db.daily_apps_totals.aggregate([ {$match: {"_id.datetime":ISODate("2013-01-28T00:00:00Z"), "_id.appId":{$type:18}}},  {$project:{_id:"$_id.appId"}}, {$sort: {_id:1}},{$limit:3}])
{
    "errmsg" : "exception: can't compare values of BSON types Array and NumberLong64",
    "code" : 16016,
    "ok" : 0
}

P.S. MongoDB shell version: 2.2.1

Answer 1

This likely means that you have some docs in your collection where _id.appId contains an array of Integer64s instead of a single Integer64.

A query object of {"_id.appId": {$type:18}} will match either due to SERVER-1475.