Question

I have an SQL table with geo-tagged values (Longitude, Latitude, value). The table is accumulated quickly and has thousands entries. Therefore, querying the table for values in some area return very large data-set.

I would like to know the way to average value with close location proximity to one value, here is an illustration:

Table:

Long            lat           value
10.123001       53.567001      10
10.123002       53.567002      12
10.123003       53.567003      18
10.124003       53.568003      13

lets say my current location is 10.123004, 53.567004. If I am querying for the values near by I will get the four raws with values 10, 12, 18, and 13. This works if the data-set is relatively small. If the data is large I would like to query sql for rounded location (10.123, 53.567) and need sql to return something like

Long            lat           value
10.123       53.567      10 (this is the average of 10, 12, and 18)
10.124       53.568      13

Is this possible? how we can average large data set based on locations?

Is sql database is the right choice in the first place?

Answer 1

GROUP BY rounded columns, and the AVG aggregate function should work fine for this:

SELECT ROUND(Long, 3) Long, 
       ROUND(Lat, 3) Lat, 
       AVG(value) 
 FROM Table
 GROUP BY ROUND(Long, 3), ROUND(Lat, 3) 

Add a WHERE clause to filter as needed.