MongoDB Fetching documents slow (Indexing used)

Question

The FETCH-stage is the limiting factor in my queries. Ive been reaserching and it seems that mongodb is reading much more than it needs, and not utilize the bandwidth fully.

Answer 1

I encountered the same problem when I was fetching around 35000 documents. To solve it, I used the aggregate function (sakulstra:aggregate) and in my case it has incredibly boosted the request. The result format is obviously not the same, but it's still easy to use to compute all things I need.

Before (7000ms) :

const historicalAssetAttributes = HistoricalAssetAttributes.find({
        date:{'$gte':startDate,'$lte':endDate},
        assetId: {$in: assetIds}
    }, {
        fields:{
            "date":1,
            "assetId":1,
            "close":1
        }
    }).fetch();

After (300ms):

const historicalAssetAttributes = HistoricalAssetAttributes.aggregate([
        {
            '$match': {
                date: {'$gte': startDate, '$lte': endDate},
                assetId: {$in: assetIds}
            }
        }, {
            '$group':{
                _id: {assetId: "$assetId"},
                close: {
                    '$push': {
                        date: "$date",
                        value: "$close"
                    }
                }
            }
        }
    ]);