Hello, I have a question about computing values in a table sorted on Date/Time field:

Table will have easily more than 10 million rows.

Input data will look like this:

Date/Time Price
Record 1: Date/Time1 15.01
Record 2: Date/Time2 15.45
Record 3: Date/Time3 15.64
Record 4: Date/Time4 16.04
Record 5: Date/Time5 15.04
Record 6: Date/Time6 15.64
Record 7: Date/Time7 15.23

I need to calculate a new column holding the average of the previous 3 rows prices and another column holding the median (50% percentile) of the previous 3 rows prices:



Date/Time Price 3-Average 3-Median
Record 1: Date/Time1 15.01 Null Null
Record 2: Date/Time2 15.45 Null Null
Record 3: Date/Time3 15.64 Null Null
Record 4: Date/Time4 16.04 15.37 15.45
Record 5: Date/Time5 15.04 15.71 15.64
Record 6: Date/Time6 15.64 15.24 15.04
Record 7: Date/Time7 15.23 15.24 15.04

Please, can you give me a hint?

Cheers

Francisco