Hi. I did reply earlier but it’s still under review for some reason. Basically I said “Apologies, I didn’t change that when I copied the document. In the original snippet “Scan” is actually “SecondEvent.Code”, and yes there is an index for that.”
I’ve also tried creating a multi index for both SecondEvent.Code and TrackTime.0 but no improvement. As I said before it’s fast when not doing anything with the result returned…
db.collection.find({'SecondEvent.Code': "1111"},
{_id: 0, 'TrackTime': 1}).sort({'TrackTime.0': -1}).limit(1)
It’s simply when adding [0].TrackTime[0].valueOf() to the end to get the time value out of the NumberLong, or even just simply adding [0] causes the massive increase in time to the query.