We need to execute geo-spatial queries where we use geo-spatial functions that operate on columns from two different tables (YELLOW_TAXI_TRIPS, TAXI_ZONES). The UDF works as a comparison to join the two tables, below is the query in which we want to improve performance applying a functional index. SELECT ZONES.zone, count(1) AS hits FROM YELLOW_TAXI_TRIPS AS TRIPS, TAXI_ZONES AS ZONES WHERE STWithinFromText('POINT('||TRIPS.PICKUP_LONGITUDE||' '||TRIPS.PICKUP_LATITUDE||')', ZONES.geom) GROUP BY ZONES.zone; ... View more