Hi,
how to calculate the 3-day moving average for this (no window functions 
):
(sample data)
{
datetime: " 2018-01-01 08:00:00"
data: {
speed: 10
}
},
datetime: " 2018-01-01 09:00:00"
data: {
speed: 15
}
},
datetime: " 2018-01-02 08:00:00"
data: {
speed: 8
}
}