// Data format
// createdAt is broken down to 1 day (for example 2019-10-21T00:00:00.000+00:00)
// Each key in the object represents an hour of that day (so key 16 represents 2019-10-21T16:00:00.000+00:00)
[{
    product: 2815,
    region: 'us',
    createdAt: ISODate(),
    location: 'Berlin',
    details: {
        16: { value: 2891, quantity: 2912, ... },
        22: { value: 2891, quantity: 2912, ... }
    }
}...]


// Aggregation
// Match returns about 600 documents and takes ~95% of the total time (4-6 secs)
const data = await this.db.collection('...').aggregate([
      { $match: { product, createdAt: { $gte: new Date(Date.now() - sevenDaysAgo) }, region } },
      { $project: { createdAt: 1, details: { $objectToArray: '$details' } } },
      { $unwind: '$details' },
      {
        $group: {
          _id: '$scannedAt',
          value: { $avg: '$details.v.value' },
          quantity: { $avg: '$details.v.quantity' },
          ...
        }
      }
    ]).sort({ _id: 1 }).toArray()