The easiest modification is to use:
calc_square_of_distance(CLIENT_LAT, CLIENT_LONG, lat, long) <
maxSquareOfTravelDist
This has the same ordering as before, but is much cheaper to calculate. You can
then calculate the actual distance in the GUI, where you're only showing a
handful of values.
cheers
stuart
________________________________________
From: Development Team [dev.and...@gmail.com]
Sent: Saturday, 11 July 2009 8:01 a.m.
To: solr-user@lucene.apache.org
Subject: How to do a "reverse distance" search?
Hi everybody,
Let's say we have 10,000 traveling sales-people spread throughout the
country. Each of them has has their own territory, and most of the
territories overlap (eg. 100 sales-people in a particular city alone). Each
of them also has a maximum distance they can travel. Some can travel
country-wide, others don't have a car and are limited to a 10mi radius.
Given that we have a client at a particular location, how do we
construct a query in Solr that finds all the sales-people who can reach that
client?
We think we have a solution for this, but I want to know what you
think. And, in SQL this is relatively easy: "select * from salespeople
where calc_distance(CLIENT_LAT, CLIENT_LONG, lat, long) < maxTravelDist" But
a problem is that calc_distance() is fairly expensive. If it was our
"client" that specified the distance, it would be easy to include it as part
of the search criteria in the Solr query, but unfortunately it's each
individual sales-person that specifies a distance.
Sincerely,
Daryl.
