Oracle Analytic Question - oracle

Question

Given a function zipdistance(zipfrom,zipto) which calculates the distance (in miles) between two zip codes and the following tables:
create table zips_required(
zip varchar2(5)
);
create table zips_available(
zip varchar2(5),
locations number(100)
);
How can I construct a query that will return to me each zip code from the zips_required table and the minimum distance that would produce a sum(locations) >= n.
Up till now we've just run an exhaustive loop querying for each radius until we've met the criteria.
--Do this over and over incrementing the radius until the minimum requirement is met
select count(locations)
from zips_required zr
left join zips_available za on (zipdistance(zr.zip,za.zip)< 2) -- Where 2 is the radius
This can take a while on a large list. It feels like this could be done with an oracle analytic query along the lines of:
min() over (
partition by zips_required.zip
order by zipdistance( zips_required.zip, zips_available.zip)
--range stuff here?
)
The only analytic queries I have done have been "row_number over (partition by order by)" based, and I'm treading into unknown areas with this. Any guidance on this is greatly appreciated.

Answer 1

This is what I came up with :
SELECT zr, min_distance
FROM (SELECT zr, min_distance, cnt,
row_number() over(PARTITION BY zr ORDER BY min_distance) rnk
FROM (SELECT zr.zip zr, zipdistance(zr.zip, za.zip) min_distance,
COUNT(za.locations) over(
PARTITION BY zr.zip
ORDER BY zipdistance(zr.zip, za.zip)
) cnt
FROM zips_required zr
CROSS JOIN zips_available za)
WHERE cnt >= :N)
WHERE rnk = 1
For each zip_required calculate the distance to the zip_available and sort them by distance
For each zip_required the count with range allows you to know how many zip_availables are in the radius of that distance.
filter (first where COUNT(locations) > N)
I used to create sample data:
INSERT INTO zips_required
SELECT to_char(10000 + 100 * ROWNUM) FROM dual CONNECT BY LEVEL <= 5;
INSERT INTO zips_available
(SELECT to_number(zip) + 10 * r, 100 - 10 * r FROM zips_required, (SELECT ROWNUM r FROM dual CONNECT BY LEVEL <= 9));
CREATE OR REPLACE FUNCTION zipdistance(zipfrom VARCHAR2,zipto VARCHAR2) RETURN NUMBER IS
BEGIN
RETURN abs(to_number(zipfrom) - to_number(zipto));
END zipdistance;
/
Note: you used COUNT(locations) and SUM(locations) in your question, I assumed it was COUNT(locations)

Answer 2

SELECT *
FROM (
SELECT zip, zd, ROW_NUMBER() OVER (PARTITION BY zip ORDER BY rn DESC) AS rn2
FROM (
SELECT zip, zd, ROW_NUMBER() OVER (PARTITION BY zip ORDER BY zd DESC) AS rn
FROM (
SELECT zr.zip, zipdistance(zr.zip, za.zip) AS zd
FROM zips_required zr
JOIN zips_available za
)
)
WHERE rn <= n
)
WHERE rn2 = 1
For each zip_required, this will select the minimal distance into which fit N zip_available's, or maximal distance if the number of zip_available's is less than N.

Answer 3

I solved the same problem by creating a subset of ZIP's within a square radius from the given zip (easy math: < or > NSWE radius ), then iterating through each entry in the subset to see if it was within the needed radius. Worked like a charm and was very fast.

Answer 4

I had partly similar requirements in one of my old projects... to calculate distance between 2 zipcodes in the US. To solve the same I had made great use of US Spatial Data. Basically the approach was to get the Source Zipcode(Latitude, Longitude) and Destination Zipcode(Latitude, Longitude).
Now then I had applied a function to get the distance based on the above. The base formula that helps in doing this calculation is available in the following site
I had also validated the outcome by referring to this site...
Note: However this will provide approximate distances, so one can use this accordingly. Benefits are once constructed its superfast to fetch the results.